chore: commit remaining pre-existing changes

- Agent configs (.opencode/agents/)
- Backend: alembic, routes, app, utils, scripts
- Frontend: package.json, vite, components, e2e infra
- Specs: 028-llm-datasource-supeset updates
- Docker e2e config and Playwright setup

frontend/.gitignore

@@ -24,3 +24,8 @@ build
 *.njsproj
 *.sln
 *.sw?
+
+# Playwright E2E test artifacts
+playwright-report/
+test-results/
+e2e/.auth/