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>

backend/.dev/reset-payment-catalog.js

@@ -0,0 +1,28 @@
+// One-shot wipe of the payment_methods + payment_method_groups tables in the
+// current DATABASE_URL. Use when you want the seed in migrate.js to repopulate
+// from scratch on the next migration run.
+//
+// Safe against payment_requests because that table does NOT FK into
+// payment_methods — `xendit_payment_method` and `product_metadata.preferred_payment_code`
+// are free-text columns.
+//
+// Usage:
+//   cd backend && node .dev/reset-payment-catalog.js
+//   cd backend && node src/db/migrate.js
+
+import 'dotenv/config'
+import { getDb } from '../src/db/client.js'
+
+const sql = getDb()
+
+const [{ count: methodCount }] = await sql`SELECT COUNT(*)::int AS count FROM payment_methods`
+const [{ count: groupCount }] = await sql`SELECT COUNT(*)::int AS count FROM payment_method_groups`
+console.log(`Before: ${methodCount} methods, ${groupCount} groups`)
+
+// FK is payment_methods.group_id → payment_method_groups (ON DELETE RESTRICT),
+// so methods must go first.
+await sql`DELETE FROM payment_methods`
+await sql`DELETE FROM payment_method_groups`
+
+console.log('Wiped. Now run: node src/db/migrate.js')
+await sql.end()