Enhance testing framework and UI feedback

- Updated architecture documentation to include details on UI rendering checks and Playwright end-to-end tests.
- Revised testing documentation to specify Playwright for frontend E2E tests and added details on running tests.
- Implemented feedback mechanism in scenario form for successful creation notifications.
- Added feedback div in ScenarioForm.html for user notifications.
- Created new fixtures for Playwright tests to manage server and browser instances.
- Developed comprehensive E2E tests for consumption, costs, equipment, maintenance, production, and scenarios.
- Added smoke tests to verify UI page loading and form submissions.
- Enhanced unit tests for simulation and validation, including new tests for report generation and validation errors.
- Created new test files for router validation to ensure consistent error handling.
- Established a new test suite for UI routes to validate dashboard and reporting functionalities.
- Implemented validation tests to ensure proper handling of JSON payloads.

tests/unit/test_validation.py

@@ -0,0 +1,28 @@
+from uuid import uuid4
+
+import pytest
+from fastapi import HTTPException
+from fastapi.testclient import TestClient
+
+
+def test_validate_json_allows_valid_payload(api_client: TestClient) -> None:
+    payload = {
+        "name": f"ValidJSON-{uuid4()}",
+        "description": "Middleware should allow valid JSON.",
+    }
+    response = api_client.post("/api/scenarios/", json=payload)
+    assert response.status_code == 200
+    data = response.json()
+    assert data["name"] == payload["name"]
+
+
+def test_validate_json_rejects_invalid_payload(api_client: TestClient) -> None:
+    with pytest.raises(HTTPException) as exc_info:
+        api_client.post(
+            "/api/scenarios/",
+            content=b"{not valid json",
+            headers={"Content-Type": "application/json"},
+        )
+
+    assert exc_info.value.status_code == 400
+    assert exc_info.value.detail == "Invalid JSON payload"