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/e2e/test_dashboard.py

@@ -0,0 +1,18 @@
+from playwright.sync_api import Page, expect
+
+
+def test_dashboard_loads_and_has_title(page: Page):
+    """Verify the dashboard page loads and the title is correct."""
+    expect(page).to_have_title("CalMiner Dashboard")
+
+
+def test_dashboard_shows_summary_metrics_panel(page: Page):
+    """Check that the summary metrics panel is visible."""
+    summary_panel = page.locator("section.panel h2:has-text('Summary Metrics')")
+    expect(summary_panel).to_be_visible()
+
+
+def test_dashboard_renders_cost_chart(page: Page):
+    """Ensure the scenario cost chart canvas is present."""
+    cost_chart = page.locator("#scenario-cost-chart")
+    expect(cost_chart).to_be_visible()