Phase 5.x payment revamp + Xendit Stage-8 prep

- Backend wraps idn-finlogos npm at /assets/payment-icons/<slug>.svg with
  1y immutable cache. Mobile drops bundled SVGs (only placeholder remains)
  and fetches via flutter_cache_manager. payment_methods.icon is now a
  CSV of slugs; catalog emits icon_urls[]. CARDS tile renders Visa + MC +
  JCB side by side.
- Per-method min/max amount bounds (BIGINT, nullable). Picker greys out
  out-of-range tiles with subtitle; backend gates with INVALID_PAYMENT_AMOUNT
  (422). Defense in depth against stale-catalog clients.
- Xendit channel codes corrected from authoritative docs
  (BCA_VA -> BCA_VIRTUAL_ACCOUNT, CREDIT_CARD -> CARDS, ovo -> ovo-new,
  shopeepay -> shopee-pay, ...). 18 methods x 5 groups seeded with
  Xendit-published per-channel min/max.
- Re-runnable seed (ON CONFLICT DO NOTHING on payment_code + new unique
  index on group name). Operator CC edits never clobbered across re-runs.
  One-shot reset + inspect scripts under backend/.dev/.
- Customer redirect HTML pages at /payment/return/{success,failure},
  brand-styled with "Buka HaloBestie" CTA firing halobestie:// deeplink.
  URL scheme registered on Android (intent-filter w/ BROWSABLE on
  MainActivity) and iOS (CFBundleURLTypes). Waiting-payment poller still
  owns confirmation; deeplink just brings the activity to foreground.
- Control center payment-catalog page: min/max inputs + columns. Other
  CC pages restyled with new theme tokens (separate work, bundled here).

169/169 backend tests pass. See requirement/phase5-payment-revamp-2026-05-27.md
for the full revamp doc. Stage 8 (E2E) still pending: webhook URL routing
decision + two client_app follow-ups (legacy /chat/request removal,
extension Custom Tab).

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

client_app/macos/Flutter/GeneratedPluginRegistrant.swift

@@ -12,6 +12,7 @@ import flutter_secure_storage_macos
 import google_sign_in_ios
 import shared_preferences_foundation
 import sign_in_with_apple
+import sqflite_darwin
 import url_launcher_macos
 
 func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
@@ -22,5 +23,6 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   FLTGoogleSignInPlugin.register(with: registry.registrar(forPlugin: "FLTGoogleSignInPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
   SignInWithApplePlugin.register(with: registry.registrar(forPlugin: "SignInWithApplePlugin"))
+  SqflitePlugin.register(with: registry.registrar(forPlugin: "SqflitePlugin"))
   UrlLauncherPlugin.register(with: registry.registrar(forPlugin: "UrlLauncherPlugin"))
 }