OAuth routes (Google/Facebook/Apple) + Android web export

- Google OAuth: /auth/google + /auth/google/callback
- Facebook OAuth: /auth/facebook + /auth/facebook/callback
- Apple Sign In placeholder
- Expo web export in mobile/dist/
- passport, passport-google-oauth20, passport-facebook installed

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

api/package.json

@@ -25,6 +25,9 @@
     "dotenv": "^17.3.1",
     "fastify": "^5.8.4",
     "ioredis": "^5.10.1",
+    "passport": "^0.7.0",
+    "passport-facebook": "^3.0.0",
+    "passport-google-oauth20": "^2.0.0",
     "pg": "^8.20.0",
     "redis": "^5.11.0",
     "uuid": "^13.0.0",