feat(auth): implement complete Google OAuth authentication system

- Add authentication module with Google OAuth 2.0 and JWT strategies
- Create secure user management with email hashing (SHA-256)
- Implement rate limiting (10 requests/minute) for auth endpoints
- Add CSRF protection and security middleware
- Create user registration with Basic plan (50 quota default)
- Add JWT-based session management with secure cookies
- Implement protected routes with authentication guards
- Add comprehensive API documentation with Swagger
- Configure environment variables for OAuth and security
- Add user profile management and quota tracking

Resolves authentication requirements §18-20:
- §18: Google OAuth 2.0 with email scope only
- §19: Auto-create User record on first OAuth callback
- §20: Store only Google UID, display name, and email hash

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/api/package.json

@@ -45,7 +45,8 @@
     "reflect-metadata": "^0.1.13",
     "rxjs": "^7.8.1",
     "uuid": "^9.0.1",
-    "stripe": "^14.10.0"
+    "stripe": "^14.10.0",
+    "cookie-parser": "^1.4.6"
   },
   "devDependencies": {
     "@nestjs/cli": "^10.0.0",
@@ -59,6 +60,7 @@
     "@types/passport-google-oauth20": "^2.0.14",
     "@types/bcrypt": "^5.0.2",
     "@types/uuid": "^9.0.7",
+    "@types/cookie-parser": "^1.4.6",
     "@typescript-eslint/eslint-plugin": "^6.0.0",
     "@typescript-eslint/parser": "^6.0.0",
     "eslint": "^8.42.0",