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>

mitra_app/lib/core/constants.dart

@@ -42,6 +42,18 @@ class ExtensionStatus {
   ExtensionStatus._();
 }
 
+/// Session topic sensitivity
+enum TopicSensitivity {
+  regular('regular'),
+  sensitive('sensitive');
+
+  final String value;
+  const TopicSensitivity(this.value);
+
+  static TopicSensitivity fromString(String? v) =>
+      values.firstWhere((e) => e.value == v, orElse: () => TopicSensitivity.regular);
+}
+
 /// WebSocket message types
 class WsMessage {
   // Auth
@@ -72,6 +84,9 @@ class WsMessage {
   static const extensionRequest = 'extension_request';
   static const extensionResponse = 'extension_response';
 
+  // Topic sensitivity
+  static const sessionTopicUpdated = 'session_topic_updated';
+
   // Delivery
   static const delivered = 'delivered';
   static const read = 'read';