feat: zero-config first-run experience with Logto bootstrap

- logto-bootstrap.sh: API-driven init script that creates SPA app,
  M2M app, and default user (camel/camel) via Logto Management API.
  Reads m-default secret from DB, then removes seeded apps with
  known secrets (security hardening). Idempotent.
- PublicConfigController: /api/config public endpoint serves Logto
  client ID from bootstrap output file (runtime, not build-time)
- Frontend: LoginPage + CallbackPage fetch config from /api/config
  instead of import.meta.env (fixes Vite build-time baking issue)
- Docker Compose: logto-bootstrap init service with health-gated
  dependency chain, shared volume for bootstrap config
- SecurityConfig: permit /api/config without auth

Flow: docker compose up → bootstrap creates apps/user → SPA fetches
config → login page shows → sign in with Logto → camel/camel

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.env.example

@@ -16,6 +16,7 @@ LOGTO_JWK_SET_URI=http://logto:3001/oidc/jwks
 LOGTO_DB_PASSWORD=change_me_in_production
 LOGTO_M2M_CLIENT_ID=
 LOGTO_M2M_CLIENT_SECRET=
+LOGTO_SPA_CLIENT_ID=
 
 # Ed25519 Keys (mount PEM files)
 CAMELEER_JWT_PRIVATE_KEY_PATH=/etc/cameleer/keys/ed25519.key