feat: Enhance end-to-end testing framework with improved server setup and UI validation

tests/e2e/test_dashboard.py

@@ -3,16 +3,15 @@ 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")
+    expect(page).to_have_title("Dashboard · CalMiner")
 
 
 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()
+    expect(page.locator("h2:has-text('Operations Overview')")).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()
+    expect(page.locator("#cost-chart")).to_be_attached()
+    expect(page.locator("#cost-chart-empty")).to_be_visible()