feat(pairing,ui): optional machine_npub + bunker_relay override + fee decimal-input UX

Three changes from the nsecbunkerd#27 bunker-pairing smoke (validated
end-to-end on the Sintra, 2026-06-21); intermingled per-file, so landed
together.

1. Optional machine_npub (model A1) — register UNPAIRED, bunker mints the
   identity at pairing:
   - machine_npub now nullable (migration m011 rebuilds dca_machines for
     sqlite / ALTER ... DROP NOT NULL for postgres; UNIQUE stays, NULLs
     don't collide so any number of unpaired machines coexist).
   - CreateMachineData.machine_npub -> str | None; create skips the
     collision-check + fee publish when blank; api_pair_machine now
     publishes the fee config after minting, so an unpaired machine clears
     its awaiting-fees gate once paired.
   - Supplying an npub up front is the DEVELOPMENT self-key path (a machine
     holding its own signing key) — available to anyone but the form field
     is explicitly marked DEVELOPMENT ONLY.
   - Frontend: npub field optional, required rule dropped, null-safe
     display (shortNpub -> "unpaired", guarded slices), empty -> null.

2. bunker_relay override on POST /machines/{id}/pair: PairMachineData gains
   bunker_relay; api_pair_machine threads it to pair_spire. Lets the seed's
   bunker:// relay differ from the relay lnbits uses to reach the bunker
   (internal docker host vs LAN/public) — needed for split-relay / dev
   deploys. Without it the smoke had to mint via a script.

3. Fees are decimal fractions, not percents: relabel super + operator fee
   inputs ("decimal fraction, 0-0.15") + a shared _assertFeesDecimal()
   guard (super/add/edit submits) so a percent typo (3 instead of 0.03)
   gets a clear toast, not a raw 400.

refs: nsecbunkerd#27/#36; aiolabs/bitspire#52; coordination smoke 2026-06-21

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

static/js/index.js

@@ -581,8 +581,29 @@ window.app = Vue.createApp({
       this.superFeeDialog.show = true
     },
 
+    // Guard the decimal-vs-percent trap shared by the super + operator fee
+    // forms: fees are decimal fractions (3% = 0.03), capped at 0.15. A value
+    // > 0.15 almost always means a percent was typed (3 instead of 0.03).
+    // Returns false + shows a clear toast so the operator never sees a raw 400.
+    _assertFeesDecimal(...fracs) {
+      if (fracs.some((v) => !Number.isFinite(v) || v < 0 || v > 0.15)) {
+        Quasar.Notify.create({
+          type: 'negative',
+          message: 'Enter each fee as a decimal fraction (e.g. 3% = 0.03)',
+          caption:
+            'Range 0–0.15. A value above 0.15 usually means a percent was typed (3 instead of 0.03).'
+        })
+        return false
+      }
+      return true
+    },
+
     async submitSuperFee() {
       const d = this.superFeeDialog.data
+      if (!this._assertFeesDecimal(
+        Number(d.super_cash_in_fee_fraction),
+        Number(d.super_cash_out_fee_fraction)
+      )) return
       this.superFeeDialog.saving = true
       try {
         const {data} = await LNbits.api.request(
@@ -699,13 +720,17 @@ window.app = Vue.createApp({
 
     async submitAddMachine() {
       const body = this._cleanMachineForm(this.addMachineDialog.data)
-      if (!body.machine_npub || !body.wallet_id) {
+      if (!body.wallet_id) {
         Quasar.Notify.create({
           type: 'negative',
-          message: 'machine_npub and wallet_id are required'
+          message: 'A wallet is required'
         })
         return
       }
+      if (!this._assertFeesDecimal(
+        Number(body.operator_cash_in_fee_fraction) || 0,
+        Number(body.operator_cash_out_fee_fraction) || 0
+      )) return
       this.addMachineDialog.saving = true
       try {
         const {data} = await LNbits.api.request('POST', MACHINES_PATH, null, body)
@@ -713,7 +738,7 @@ window.app = Vue.createApp({
         this.addMachineDialog.show = false
         Quasar.Notify.create({
           type: 'positive',
-          message: `Machine ${data.name || data.machine_npub.slice(0, 12)} added`
+          message: `Machine ${data.name || (data.machine_npub || 'unpaired').slice(0, 12)} added`
         })
       } catch (e) {
         this._notifyError(e, 'Failed to add machine')
@@ -741,6 +766,10 @@ window.app = Vue.createApp({
 
     async submitEditMachine() {
       const d = this.editMachineDialog.data
+      if (!this._assertFeesDecimal(
+        Number(d.operator_cash_in_fee_fraction) || 0,
+        Number(d.operator_cash_out_fee_fraction) || 0
+      )) return
       this.editMachineDialog.saving = true
       try {
         const {data} = await LNbits.api.request(
@@ -772,7 +801,7 @@ window.app = Vue.createApp({
       Quasar.Dialog.create({
         title: 'Delete machine?',
         message:
-          `This removes <b>${machine.name || machine.machine_npub.slice(0, 12)}</b>` +
+          `This removes <b>${machine.name || (machine.machine_npub || 'unpaired').slice(0, 12)}</b>` +
           ' from your fleet. Existing settlements and payment history are preserved' +
           ' — only the machine row itself is removed. Continue?',
         html: true,
@@ -848,7 +877,7 @@ window.app = Vue.createApp({
       Quasar.Dialog.create({
         title: 'Revoke spire access?',
         message:
-          `This cuts <b>${machine.name || machine.machine_npub.slice(0, 12)}</b>'s` +
+          `This cuts <b>${machine.name || (machine.machine_npub || 'unpaired').slice(0, 12)}</b>'s` +
           ' signing access at the bunker — the spire can no longer submit' +
           ' cash-outs until you re-pair it. Continue?',
         html: true,
@@ -1515,7 +1544,7 @@ window.app = Vue.createApp({
     // Helpers
     // -----------------------------------------------------------------
     shortNpub(npub) {
-      if (!npub) return ''
+      if (!npub) return 'unpaired'
       if (npub.length <= 16) return npub
       return npub.slice(0, 8) + '…' + npub.slice(-6)
     },
@@ -1601,7 +1630,7 @@ window.app = Vue.createApp({
 
     _cleanMachineForm(d) {
       return {
-        machine_npub: (d.machine_npub || '').trim(),
+        machine_npub: (d.machine_npub || '').trim() || null,
         wallet_id: d.wallet_id,
         name: (d.name || '').trim() || null,
         location: (d.location || '').trim() || null,