fix: align CI tests with current UI text and database naming

Backend conftest.py was hardcoded to patherly_test but CI creates
resolutionflow_test — now reads DATABASE_URL env var first. E2E tests
had stale placeholder text, heading, and landing page assertions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/e2e/navigation.spec.ts

@@ -14,7 +14,7 @@ test.describe('authenticated navigation smoke tests', () => {
     await page.goto('/sessions')
 
     await expect(
-      page.getByRole('heading', { name: 'Session History' }),
+      page.getByRole('heading', { name: 'Sessions' }),
     ).toBeVisible()
   })