feat: add knowledge version history (closes #75, closes #76)

- Added EntryVersion model with author relation
- Implemented automatic versioning on entry create/update
- Added API endpoints for version history:
  - GET /api/knowledge/entries/:slug/versions - list versions
  - GET /api/knowledge/entries/:slug/versions/:version - get specific
  - POST /api/knowledge/entries/:slug/restore/:version - restore version
- Created VersionHistory.tsx component with timeline view
- Added History tab to entry detail page
- Supports version viewing and restoring
- Includes comprehensive tests for version operations
- All TypeScript types are explicit and type-safe

apps/web/src/components/knowledge/index.ts

@@ -5,3 +5,4 @@
 export { EntryViewer } from "./EntryViewer";
 export { EntryEditor } from "./EntryEditor";
 export { EntryMetadata } from "./EntryMetadata";
+export { VersionHistory } from "./VersionHistory";