refactor(v2): canonical sat-amount vocabulary + delete Lamassu-era reverse-derivation

Cross-codebase decision logged at memory `reference_sat_amount_vocabulary.md`
and at `~/dev/coordination/log.md` (2026-05-26). Canonical names with
explicit units across satmachineadmin, lamassu-next, atm-tui:

  - `wire_sats` — actual Lightning payment amount (direction-agnostic;
                  was `gross_sats`, only "gross" for cash-out)
  - `principal_sats` — market-rate sats before commission (unchanged)
  - `fee_sats` — commission (was `commission_sats` internally;
                 already the wire format)
  - `fee_fraction` — commission rate as unit fraction in [0, 1]
                     (was `*_pct` / `fee_percent`; eliminates the
                     latent 100x bug from `feePercent * 100` on the
                     lamassu-next side)

Invariants enforced in bitspire._assert_sat_invariants on every
parsed settlement — range (all sats >= 0, 0 <= fee_fraction <= 1) +
direction-specific sum:

  - cash-out: wire_sats == principal_sats + fee_sats
  - cash-in:  wire_sats == principal_sats - fee_sats
              AND fee_sats <= principal_sats

Breaches raise SettlementInvariantError; tasks._handle_payment
records the row as `status='rejected'` with the exception message
and skips distribution. Attribution failure path symmetric.

Schema changes (m001 + m006):

  - dca_settlements.gross_sats              -> wire_sats
  - dca_settlements.commission_sats         -> fee_sats
  - super_config.super_fee_pct              -> super_fee_fraction
  - dca_commission_splits.pct               -> fraction
  - dca_machines.fallback_commission_pct    DROPPED (obsolete)
  - dca_settlements.used_fallback_split     DROPPED (obsolete)

m006 idempotently renames + drops columns on existing installs;
m001 lays down the canonical schema for fresh installs.

Obsolete code removed (Lamassu-era reverse-derivation):

  - calculations.calculate_commission — back-derived principal+fee
    from gross-with-commission-baked-in. v2 stamps both directly.
  - calculations.calculate_exchange_rate — bitSpire stamps directly.
  - bitspire._parse_fallback — sole caller of calculate_commission.
  - Machine.fallback_commission_fraction — only read by _parse_fallback.
  - DcaSettlement.used_fallback_split — only written by _parse_fallback.

parse_settlement now raises SettlementMetadataError if Payment.extra
lacks the bitSpire stamp or required absolute sat fields. No silent
back-derivation; upstream-bug surfacing via dashboard rejection.

Frontend (JS + Quasar templates) updated for the column renames and
the removed fallback fields. Settlements table renders "Wire" + "Fee"
columns; the "(fallback split)" warning badge is gone.

Tests:
  - test_calculations.py: kept distribution tests; deleted
    calculate_commission + calculate_exchange_rate tests.
  - test_two_stage_split.py: renamed variables; rewrote docstring
    value literals (e.g. `super_fee_fraction=0.30` not `=30%`).
  - test_nostr_attribution.py: dropped fallback_commission_fraction
    from machine fixture.
  - 72/72 pass on regtest container.

Cross-codebase follow-ups tracked in coordination log:
  - lamassu-next: rename `fee_percent` -> `fee_fraction` on
    Payment.extra + state.db; drop the `* 100` at lightning.ts:780.
  - atm-tui: read `fee_fraction` column in db.zig.

Memory artefacts:
  - reference_sat_amount_vocabulary.md (canonical + invariants)
  - feedback_pct_to_fraction_renames_need_value_sweep.md (gotcha)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

templates/satmachineadmin/index.html

@@ -31,13 +31,13 @@
     <q-banner
       v-if="superConfig"
       class="q-mb-md"
-      :class="superConfig.super_fee_pct > 0 ? 'bg-blue-1 text-grey-9' : 'bg-grey-2 text-grey-9'">
+      :class="superConfig.super_fee_fraction > 0 ? 'bg-blue-1 text-grey-9' : 'bg-grey-2 text-grey-9'">
       <template v-slot:avatar>
-        <q-icon name="account_balance" :color="superConfig.super_fee_pct > 0 ? 'blue' : 'grey'"></q-icon>
+        <q-icon name="account_balance" :color="superConfig.super_fee_fraction > 0 ? 'blue' : 'grey'"></q-icon>
       </template>
       <span :style="{fontWeight: 500}">
         LNbits platform fee:
-        <span :style="{color: '#1976d2'}">${ (superConfig.super_fee_pct * 100).toFixed(2) }%</span>
+        <span :style="{color: '#1976d2'}">${ (superConfig.super_fee_fraction * 100).toFixed(2) }%</span>
         of each transaction's commission.
       </span>
       <span :style="{opacity: 0.7, fontSize: '0.85em'}" class="q-ml-sm">
@@ -143,12 +143,6 @@
                         v-text="shortId(props.row.wallet_id)"></code>
                 </q-td>
                 <q-td key="fiat_code" v-text="props.row.fiat_code"></q-td>
-                <q-td key="fallback_commission_pct">
-                  <span v-text="(props.row.fallback_commission_pct * 100).toFixed(2) + '%'"></span>
-                  <q-tooltip>
-                    Used only when bitSpire doesn't supply a per-tx split.
-                  </q-tooltip>
-                </q-td>
                 <q-td key="actions" auto-width>
                   <q-btn flat dense round size="sm" icon="visibility"
                          color="primary"
@@ -529,13 +523,13 @@
                       dense outlined></q-input>
                   </div>
                   <div class="col-5 col-md-3">
-                    <q-input v-model.number="leg.pct"
+                    <q-input v-model.number="leg.fraction"
                       label="% (0..1)"
                       type="number" step="0.01" min="0" max="1"
                       dense outlined>
                       <template v-slot:append>
                         <span :style="{fontSize: '0.75em', opacity: 0.6}"
-                              v-text="((leg.pct || 0) * 100).toFixed(1) + '%'"></span>
+                              v-text="((leg.fraction || 0) * 100).toFixed(1) + '%'"></span>
                       </template>
                     </q-input>
                   </div>
@@ -630,8 +624,8 @@
                     <span :style="{fontSize: '0.85em'}"
                           v-text="formatTime(props.row.created_at)"></span>
                   </q-td>
-                  <q-td key="gross_sats" class="text-right">
-                    <span v-text="formatSats(props.row.gross_sats)"></span>
+                  <q-td key="wire_sats" class="text-right">
+                    <span v-text="formatSats(props.row.wire_sats)"></span>
                   </q-td>
                   <q-td key="error_message">
                     <span :style="{fontSize: '0.85em', opacity: 0.8}"
@@ -792,14 +786,6 @@
             dense outlined
             :rules="[v => !!v || 'Pick a wallet']"></q-select>
 
-          <q-input
-            v-model.number="addMachineDialog.data.fallback_commission_pct"
-            label="Fallback commission % (decimal: 0.05 = 5%)"
-            hint="Only used if bitSpire doesn't supply a per-tx split (lamassu-next#44)."
-            type="number" step="0.0001" min="0" max="1"
-            class="q-mb-md"
-            dense outlined></q-input>
-
           <q-input
             v-model="addMachineDialog.data.fiat_code"
             label="Fiat code"
@@ -855,12 +841,6 @@
               <div class="text-caption" :style="{opacity: 0.6}">Location</div>
               <span v-text="machineDetail.machine.location || '—'"></span>
             </div>
-            <div class="col-6 col-md-3">
-              <div class="text-caption" :style="{opacity: 0.6}">
-                Fallback commission %
-              </div>
-              <span v-text="(machineDetail.machine.fallback_commission_pct * 100).toFixed(2) + '%'"></span>
-            </div>
           </div>
 
           <q-separator class="q-mb-md"></q-separator>
@@ -893,27 +873,19 @@
                 <q-td key="status">
                   <q-badge :color="settlementStatusColor(props.row.status)"
                            :label="props.row.status"></q-badge>
-                  <q-icon v-if="props.row.used_fallback_split"
-                          name="warning_amber" color="orange" size="sm"
-                          class="q-ml-xs">
-                    <q-tooltip>
-                      Fallback split — bitSpire didn't supply per-tx
-                      net/fee. See lamassu-next#44.
-                    </q-tooltip>
-                  </q-icon>
                 </q-td>
                 <q-td key="created_at">
                   <span :style="{fontSize: '0.85em'}"
                         v-text="formatTime(props.row.created_at)"></span>
                 </q-td>
-                <q-td key="gross_sats" class="text-right">
-                  <span v-text="formatSats(props.row.gross_sats)"></span>
+                <q-td key="wire_sats" class="text-right">
+                  <span v-text="formatSats(props.row.wire_sats)"></span>
                 </q-td>
                 <q-td key="principal_sats" class="text-right">
                   <span v-text="formatSats(props.row.principal_sats)"></span>
                 </q-td>
-                <q-td key="commission_sats" class="text-right">
-                  <span v-text="formatSats(props.row.commission_sats)"></span>
+                <q-td key="fee_sats" class="text-right">
+                  <span v-text="formatSats(props.row.fee_sats)"></span>
                   <div :style="{fontSize: '0.75em', opacity: 0.6}">
                     super
                     <span v-text="formatSats(props.row.platform_fee_sats)"></span>
@@ -996,7 +968,7 @@
               <q-icon name="info" color="blue"></q-icon>
             </template>
             Original gross:
-            <b v-text="formatSats(partialDispenseDialog.settlement.gross_sats)"></b>.
+            <b v-text="formatSats(partialDispenseDialog.settlement.wire_sats)"></b>.
             Provide what was actually dispensed. Sat amounts will scale linearly,
             the commission split will recompute, and distribution will re-run.
           </q-banner>
@@ -1019,7 +991,7 @@
                 label="Dispensed sats"
                 hint="Exact sat amount actually dispensed (≤ original gross)"
                 type="number" step="1" min="0"
-                :max="partialDispenseDialog.settlement.gross_sats"
+                :max="partialDispenseDialog.settlement.wire_sats"
                 dense outlined></q-input>
             </q-tab-panel>
           </q-tab-panels>
@@ -1085,7 +1057,7 @@
             Operators see this as a read-only banner. Wallet ID is where the
             collected fee lands; typically a wallet you (the super) own.
           </p>
-          <q-input v-model.number="superFeeDialog.data.super_fee_pct"
+          <q-input v-model.number="superFeeDialog.data.super_fee_fraction"
             label="Fee % (decimal, 0..1)"
             hint="0.30 = 30% of every operator's commission"
             type="number" step="0.0001" min="0" max="1"
@@ -1337,10 +1309,6 @@
             emit-value map-options
             class="q-mb-md"
             dense outlined></q-select>
-          <q-input v-model.number="editMachineDialog.data.fallback_commission_pct"
-            label="Fallback commission %"
-            type="number" step="0.0001" min="0" max="1"
-            class="q-mb-md" dense outlined></q-input>
           <q-input v-model="editMachineDialog.data.fiat_code"
             label="Fiat code" class="q-mb-md" dense outlined></q-input>
           <q-toggle v-model="editMachineDialog.data.is_active"