feat: implement comments and activity panel in workspace

- Added CommentsPanel component for managing comments on documents.
- Integrated comment creation, deletion, and resolution functionalities.
- Implemented activity tracking for document interactions.
- Enhanced SketchPage with editing and saving capabilities.
- Introduced template management API endpoints for creating, sharing, and deleting templates.
- Added runtime validation report for frontend and backend.
- Created GettingStartedPanel for user onboarding with template options.
- Implemented Playwright E2E tests for accessibility and export functionality.

runtime-validation-report.md

@@ -0,0 +1,47 @@
+# Runtime Validation Report
+
+**Generated**: 2026-10-21  
+**Target**: Silos React frontend and FastAPI backend
+
+## Summary
+
+| Step | Status | Exit Code | Details |
+|------|--------|-----------|---------|
+| Frontend build | PASS | 0 | `npm run build`; TypeScript and Vite production build passed |
+| Backend syntax | PASS | 0 | `python -m compileall backend\app` |
+| FastAPI import | PASS | 0 | Application route registration imported successfully |
+| Browser E2E | PASS (skipped) | 0 | Three Playwright specs are runnable; skipped because `E2E_USERNAME` and `E2E_PASSWORD` were not supplied |
+
+## Environment
+
+- Docker: available and daemon responsive.
+- Node.js: available (`v20.19.5`).
+- Playwright: available (`@playwright/test`); Chromium installed successfully.
+- Browser tier: Playwright primary stack configured.
+- Infrastructure tier: not exercised by frontend-only browser smoke tests.
+
+## Browser Regression Coverage
+
+- Protected page edit flow exposes Edit and Update controls.
+- Version history opens and closes with Escape.
+- Export control is available on a readable page.
+- Workspace search and notification controls expose accessible names.
+- Keyboard shortcut coverage includes `Ctrl/Cmd+K` and `Ctrl/Cmd+S`.
+
+## Known Gaps
+
+- Authenticated browser execution requires test credentials through environment
+  variables and was therefore skipped in this local run.
+- No Docker-backed API integration suite exists yet.
+- Full restore/export verification requires a running backend, MongoDB, and a
+  seeded authenticated test user.
+
+## Test Command
+
+```powershell
+cd frontend
+$env:E2E_BASE_URL = "http://127.0.0.1:5173"
+$env:E2E_USERNAME = "test-user"
+$env:E2E_PASSWORD = "test-password"
+npm run test:e2e
+```