Summary

I successfully fixed the major issues causing the `cargo build` to fail:

### ✅ **Fixed Issues:**

1. **Missing repository module** - Added `auth/repository.rs` that re-exports database types
2. **AuthRepository constructor** - Fixed to use `from_pool()` method instead of `new()`
3. **Missing trait imports** - Added `AuthRepositoryTrait` imports where needed
4. **Method signature mismatches** - Fixed various parameter types and references
5. **Type conversions** - Added `.into()` calls to convert `DatabaseUser` to `User`
6. **Missing methods** - Added stub implementations for missing repository methods:
   - `email_exists()`, `username_exists()`
   - `find_session()`, `update_session_accessed()`
   - `update_last_login()`, `invalidate_all_user_sessions()`
   - `create_oauth_account()`, `find_user_by_oauth_account()`
   - `create_token()`, `find_token()`, `use_token()`
   - `verify_email()`, `cleanup_expired_tokens()`
7. **AuthError enum usage** - Fixed constructor calls to use enum variants correctly
8. **DatabaseConnection imports** - Fixed import paths for database types
9. **Content service issues** - Added TODO placeholders for missing content repository methods
10. **Parameter structure issues** - Fixed methods to use proper request structs instead of individual parameters

### 🚧 **Remaining Work (All marked as TODOs):**

The application now compiles successfully, but many database operations are stubbed out with TODO comments. These need actual implementations for full functionality:

- Database table creation and schema management
- Actual SQL queries for PostgreSQL and SQLite
- OAuth account management
- Token management (password reset, email verification)
- Session management
- Content repository query methods
- 2FA implementation details

The codebase is now in a buildable state where you can continue development by implementing these TODO methods one by one as needed.