feat(loyalty): Phase 1 production launch hardening

Phase 1 of the loyalty production launch plan: config & security
hardening, dropped-data fix, DB integrity guards, rate limiting, and
constant-time auth compare. 362 tests pass.

- 1.4 Persist customer birth_date (new column + migration). Enrollment
  form was collecting it but the value was silently dropped because
  create_customer_for_enrollment never received it. Backfills existing
  customers without overwriting.
- 1.1 LOYALTY_GOOGLE_SERVICE_ACCOUNT_JSON validated at startup (file
  must exist and be readable; ~ expanded). Adds is_google_wallet_enabled
  and is_apple_wallet_enabled derived flags. Prod path documented as
  ~/apps/orion/google-wallet-sa.json.
- 1.5 CHECK constraints on loyalty_cards (points_balance, stamp_count
  non-negative) and loyalty_programs (min_purchase, points_per_euro,
  welcome_bonus non-negative; stamps_target >= 1). Mirrored as
  CheckConstraint in models. Pre-flight scan showed zero violations.
- 1.3 @rate_limit on store mutating endpoints: stamp 60/min,
  redeem/points-earn 30-60/min, void/adjust 20/min, pin unlock 10/min.
- 1.2 Constant-time hmac.compare_digest for Apple Wallet auth token
  (pulled forward from Phase 9 — code is safe whenever Apple ships).

See app/modules/loyalty/docs/production-launch-plan.md for the full
launch plan and remaining phases.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/modules/loyalty/services/apple_wallet_service.py

@@ -9,6 +9,7 @@ Handles Apple Wallet integration including:
 """
 
 import hashlib
+import hmac
 import io
 import json
 import logging
@@ -95,7 +96,12 @@ class AppleWalletService:
         if authorization and authorization.startswith("ApplePass "):
             auth_token = authorization.split(" ", 1)[1]
 
-        if not auth_token or auth_token != card.apple_auth_token:
+        # Constant-time compare to avoid leaking the token via timing.
+        if (
+            not auth_token
+            or not card.apple_auth_token
+            or not hmac.compare_digest(auth_token, card.apple_auth_token)
+        ):
             raise InvalidAppleAuthTokenException()
 
     def generate_pass_safe(self, db: Session, card: LoyaltyCard) -> bytes: