feat(v2): CRUD + per-direction fee cap validation (#38 2/5)

Wires the new directional fee fields through the write path and adds
the 15%-per-direction cap guard at the API boundary.

CRUD:
- create_machine INSERT includes operator_cash_in_fee_fraction +
  operator_cash_out_fee_fraction (Pydantic default 0 covers existing
  callers).
- update_machine + update_super_config already use generic update_data
  dict, so the new fields flow through without per-call changes.

API boundary (views_api.py):
- _assert_machine_fee_cap_safe(operator_in, operator_out) — pairs
  candidates against current super-config, rejects if (super_X +
  operator_X) > 0.15 for either direction. Called from api_create_machine
  + api_update_machine (with partial-PATCH semantics: unset fields keep
  the machine's current value).
- _assert_super_config_cap_safe(new_super_in, new_super_out) — fetches
  every active machine; rejects with offending-machine name in the 400
  detail if any (effective_super + operator) > cap. Called from
  api_update_super_config.

Cap rounding: float arithmetic rounds (super + operator) to 4 decimals
(DECIMAL(10,4) precision) before comparing, so the IEEE 754 surprise
0.10 + 0.05 = 0.15000000000000002 doesn't trip the cap.

Tests (13 cases, all green): both directions hit the cap, exact-cap
acceptance, no-super-config degenerate path, partial PATCH on
super-config, offending-machine name in error detail, empty-fleet
vacuous safety.

Refs: aiolabs/satmachineadmin#38 (Layer 1), coord-log §2026-06-01T07:22Z
(cap lock at 15% per direction, defense in depth).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crud.py

@@ -80,9 +80,13 @@ async def create_machine(operator_user_id: str, data: CreateMachineData) -> Mach
         """
         INSERT INTO satoshimachine.dca_machines
         (id, operator_user_id, machine_npub, wallet_id, name, location,
-         fiat_code, is_active, created_at, updated_at)
+         fiat_code, is_active,
+         operator_cash_in_fee_fraction, operator_cash_out_fee_fraction,
+         created_at, updated_at)
         VALUES (:id, :operator_user_id, :machine_npub, :wallet_id, :name,
-                :location, :fiat_code, :is_active, :created_at, :updated_at)
+                :location, :fiat_code, :is_active,
+                :operator_cash_in_fee_fraction, :operator_cash_out_fee_fraction,
+                :created_at, :updated_at)
         """,
         {
             "id": machine_id,
@@ -93,6 +97,8 @@ async def create_machine(operator_user_id: str, data: CreateMachineData) -> Mach
             "location": data.location,
             "fiat_code": data.fiat_code,
             "is_active": True,
+            "operator_cash_in_fee_fraction": data.operator_cash_in_fee_fraction,
+            "operator_cash_out_fee_fraction": data.operator_cash_out_fee_fraction,
             "created_at": now,
             "updated_at": now,
         },