Phase 4 Stage 2: onboarding redesign (client_app + mitra_app)

Verif Choice Sheet on display_name_screen drives the user into either
the verified or anonymous onboarding sub-flow. ESP screen (12 chips,
multi-select, info-only) + USP screen are shared between both branches;
selections persist through to chat_sessions.topics on session start.

OTP-blocked popup (HaloPopup) listens for the four real OTP-rate-limit
error codes (OTP_RATE_LIMIT_PHONE, OTP_RATE_LIMIT_IP, OTP_COOLDOWN,
OTP_ATTEMPTS_EXCEEDED) and drops the user onto the anonymous path with
ESP/USP state preserved.

Auth-providers gating replaces the --dart-define=ENABLE_SOCIAL_AUTH
build flag with server-driven discovery. authProvidersProvider preloads
GET /api/shared/auth-providers at cold start; welcome/register/
force-register screens render Google/Apple buttons only when the
backend reports enabled:true. Falls back to phone-OTP-only when both
providers are off. social_auth_enabled.dart deleted; client_app/CLAUDE.md
updated to reflect the new gating contract.

Mitra app: chat screen renders an ESP chip strip above the first message
bubble when chat_sessions.topics is non-empty.

Backend session.service.js getSessionById SELECTs cs.topics so the mitra
side can read the customer's selected topics.

Maestro flows 02_onboarding_verified.yaml + 03_onboarding_anon.yaml.

Deviation from plan: plan referenced OTP error code 'otp_retry_exhausted';
real codes are OTP_RATE_LIMIT_*/OTP_COOLDOWN/OTP_ATTEMPTS_EXCEEDED -
popup listens for all four. Plan said 'has_paid_first_session'; live
endpoint returns 'has_consulted_before' - used the live field.

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

client_app/CLAUDE.md

@@ -9,7 +9,7 @@ Flutter mobile application for end users (clients) seeking mental health support
 - **Framework:** Flutter (iOS + Android)
 - **Auth:** Self-managed (Phase 3.4). Anonymous-first + phone OTP + (Google / Apple when creds arrive).
   - Access token in memory on `AuthBridge`; refresh token persisted via `flutter_secure_storage`.
-  - Google + Apple SDKs installed but buttons are hidden behind `--dart-define=ENABLE_SOCIAL_AUTH=true` until backend OAuth credentials exist.
+  - Google + Apple SDKs installed; buttons are gated server-side via `GET /api/shared/auth-providers` (cached on cold start in `authProvidersProvider`). Buttons render only when the corresponding env-driven flag returns `enabled: true`.
   - `firebase_auth` removed; `firebase_messaging` kept for FCM push.
 - **API:** Calls public Fastify backend (`/api/client/` and `/api/shared/` routes). Refresh + logout live on `shared.auth`.
 - **Payment:** Xendit (paid sessions, optional trial)
@@ -25,4 +25,4 @@ Flutter mobile application for end users (clients) seeking mental health support
 - Never call `/api/mitra/` or `/internal/` routes from this app
 - API calls go through `ApiClient`; it auto-attaches the JWT from `AuthBridge` and auto-refreshes on 401
 - WebSocket handshake (`/api/shared/ws`) reads the access token from `AuthBridge` in the first frame's `{type:"auth", token, session_id?}` message
-- Use `const bool.fromEnvironment('ENABLE_SOCIAL_AUTH')` (via `social_auth_enabled.dart`) to gate any Google/Apple UI — never call `loginGoogle` / `loginApple` from a path reachable without that flag
+- Read `authProvidersProvider` (`core/auth/auth_providers_provider.dart`) to gate any Google/Apple UI — never call `loginGoogle` / `loginApple` from a path reachable when `providers.google` / `providers.apple` is `false`