feat(auth): implement user registration and login with JWT authentication

- Added `bcrypt`, `jsonwebtoken`, and `once_cell` dependencies to manage password hashing and JWT handling.
- Created `Claims` struct for JWT claims and implemented token generation in the login route.
- Implemented user registration and authentication logic in the `auth` module.
- Updated error handling to include validation errors.
- Created new routes for user registration and login, and integrated them into the main router.
- Added tests for the authentication flow, including registration and login scenarios.
- Updated user model to include a password hash field.
- Refactored user creation logic to include password validation.
- Adjusted feed and user routes to utilize JWT for authentication.

thoughts-backend/api/src/error/adapter.rs

@@ -34,6 +34,7 @@ impl HTTPError for UserError {
             UserError::Forbidden => StatusCode::FORBIDDEN,
             UserError::UsernameTaken => StatusCode::BAD_REQUEST,
             UserError::AlreadyFollowing => StatusCode::BAD_REQUEST,
+            UserError::Validation(_) => StatusCode::UNPROCESSABLE_ENTITY,
             UserError::Internal(_) => StatusCode::INTERNAL_SERVER_ERROR,
         }
     }