Phase 3.3: topic sensitivity + Phase 3.4: auth foundation

Phase 3.3 — Session Topic Sensitivity (complete):
- Backend: topic_sensitivity column + session_sensitivity_log, sensitivity service
  (flip with one-way-latch + audit), PATCH /api/shared/chat/sessions/:id/topic,
  topic carried in pairing + extension WS payloads, CC filter + sensitive stats
  + per-mitra sensitive columns on activity page
- client_app: TopicSelectionBottomSheet before pricing, topic flows through
  pairing request, silent WS handler for session_topic_updated
- mitra_app: SensitivityBadge + SensitivityTheme + sensitivityConfigProvider,
  overlay badge + yellow accent, chat screen app-bar toggle with configurable
  confirmation + latch, extension card shows current flag, history + transcript
  yellow theme
- control_center: Sensitivitas Topik settings section, topic filter + column
  with inline audit log, sensitive stats dashboard card, mitra activity
  sensitive columns with QC flag

Phase 3.4 — Self-Managed Auth (foundation only):
- Migration: auth_sessions + otp_requests tables, social identity columns on
  customers, password_hash + lockout on control_center_users, OTP + CC lockout
  app_config keys
- New services: password (bcrypt + complexity), token (JWT HS256 + refresh
  rotation, session_id claim pre-wires future Valkey revocation),
  social-identity (Google + Apple JWKS), OTP (Fazpass stub — real API TBD)
- Constants: AuthProvider + OtpChannel
- Middleware, auth route rewrites, WS auth update, Firebase → FCM isolation
  still pending (next chunk); Fazpass docs + Apple Developer setup still
  required before E2E testing

Docs:
- requirement/phase3.3.md, phase3.3-plan.md, phase3.3-testing.md
- requirement/phase3.4.md, phase3.4-plan.md

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

backend/src/constants.js

@@ -59,6 +59,27 @@ export const EndedBy = Object.freeze({
   MITRA: 'mitra',
 })
 
+// Session topic sensitivity
+export const TopicSensitivity = Object.freeze({
+  REGULAR: 'regular',
+  SENSITIVE: 'sensitive',
+})
+
+// Auth provider used to establish a session
+export const AuthProvider = Object.freeze({
+  ANONYMOUS: 'anonymous',
+  PHONE: 'phone',
+  GOOGLE: 'google',
+  APPLE: 'apple',
+  PASSWORD: 'password',
+})
+
+// OTP delivery channel
+export const OtpChannel = Object.freeze({
+  WHATSAPP: 'whatsapp',
+  SMS: 'sms',
+})
+
 // WebSocket message types
 export const WsMessage = Object.freeze({
   // Auth
@@ -93,6 +114,9 @@ export const WsMessage = Object.freeze({
   EXTENSION_REQUEST: 'extension_request',
   EXTENSION_RESPONSE: 'extension_response',
 
+  // Topic sensitivity
+  SESSION_TOPIC_UPDATED: 'session_topic_updated',
+
   // Early end
   EARLY_END: 'early_end',