Update Coolify deployment guide to clarify production and development dependencies; refactor import statements for consistency and add requirements-dev.txt for development dependencies.

Co-authored-by: Copilot <copilot@github.com>

docs/deployment/coolify.md

@@ -65,6 +65,8 @@ Add these as **Runtime** environment variables in Coolify:
    ```
 8. Click **Create Resource**
 
+> **Note:** The frontend uses `requirements.txt` for production dependencies and `requirements-dev.txt` for development dependencies (like pytest). Nixpacks will automatically detect and install only the production dependencies.
+
 > **Important:** Nixpacks copies the **contents** of the Base Directory to `/app/` in the container. When Base Directory is `/frontend`, the `frontend/` folder wrapper is removed — only `app/`, `tests/`, and `requirements.txt` are copied. Therefore the start command uses `app.main:app` (not `frontend.app.main:app`).
 
 ### Frontend Environment Variables

frontend/app/main.py

@@ -13,7 +13,7 @@ from flask import (
     url_for,
 )
 
-from frontend.app.config import Config
+from .config import Config
 
 app = Flask(__name__)
 app.config.from_object(Config)

frontend/requirements-dev.txt

@@ -0,0 +1,2 @@
+pytest
+pytest-mock

frontend/tests/test_frontend.py

@@ -6,7 +6,7 @@ from unittest.mock import MagicMock, patch
 os.environ.setdefault("FLASK_SECRET_KEY", "test-secret")
 os.environ.setdefault("BACKEND_URL", "http://backend-mock")
 
-from frontend.app.main import app  # noqa: E402
+from app.main import app  # noqa: E402
 
 
 @pytest.fixture