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.

frontend/e2e/phase8-history.spec.ts

@@ -0,0 +1,16 @@
+import { test, expect } from '@playwright/test'
+import { login } from './helpers'
+
+test('protected page editing exposes history and restore controls', async ({ page }) => {
+  test.skip(!process.env.E2E_USERNAME || !process.env.E2E_PASSWORD, 'Set E2E_USERNAME and E2E_PASSWORD')
+  expect(await login(page)).toBeTruthy()
+  await page.getByRole('link', { name: /recent|pages|silo/i }).first().click().catch(() => {})
+  const edit = page.getByRole('button', { name: /^edit$/i }).first()
+  await expect(edit).toBeVisible()
+  await edit.click()
+  await expect(page.getByRole('button', { name: /update/i })).toBeEnabled()
+  await page.getByRole('button', { name: /version history/i }).click()
+  await expect(page.getByRole('heading', { name: /version history/i })).toBeVisible()
+  await page.keyboard.press('Escape')
+  await expect(page.getByRole('heading', { name: /version history/i })).toHaveCount(0)
+})