docs: update project docs and clean up redundant files

- PROGRESS.md: update to 2026-05-29 with security hardening (T-005),
  4-frontend architecture, AI provider refactoring, discovery features,
  landing page/referral/quota, desktop layout, admin AI management
- AGENTS.md: add AI provider list (Alibaba/NVIDIA, removed Claude/DeepL/Local),
  DB-driven config, CSRF/rate-limit/CORS notes, admin_ai reload quirk
- .env.example: sync with actual config, replace deprecated providers
  with current Sensenova/OpencodeGo/NVIDIA/Spark/Alibaba
- docs/PROJECT_STATUS.md: archive (fully superseded by PROGRESS.md)
- Remove generated JS files (_bing_search.js, _batch_search.js)
- Remove empty directories (data/corpus, data/models)
- Remove backend/.coverage (test artifact)
- Fix services/.gitignore to cover _bing_search.js
- Include pending AI provider DB admin feature (admin_ai, AIProvider model,
  AIProviders.vue, migration) and T-008 test report

backend/app/api/v1/__init__.py

@@ -0,0 +1,39 @@
+from . import auth
+from . import marketing
+from . import translate
+from . import customer
+from . import quotation
+from . import whatsapp
+from . import product
+from . import exchange
+from . import push
+from . import admin
+from . import analytics
+from . import teams
+from . import onboarding
+from . import notification
+from . import feedback
+from . import payment
+from . import interaction
+from . import silent_pattern
+from . import training
+from . import followup
+from . import ai_assistant
+from . import discovery
+from . import discovery_record
+from . import certification
+from . import invoice
+from . import usage
+from . import referral
+from . import admin_search
+from . import search
+from . import admin_ai
+
+__all__ = [
+    'auth', 'marketing', 'translate', 'customer', 'quotation', 'whatsapp',
+    'product', 'exchange', 'push', 'admin', 'analytics', 'teams',
+    'onboarding', 'notification', 'feedback', 'payment', 'interaction',
+    'silent_pattern', 'training', 'followup', 'ai_assistant', 'discovery',
+    'discovery_record', 'certification', 'invoice', 'usage', 'referral',
+    'admin_search', 'search', 'admin_ai'
+]