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/api/src/knowledge/entities/knowledge-entry-version.entity.ts

@@ -0,0 +1,39 @@
+/**
+ * Knowledge Entry Version entity
+ * Represents a historical version of a knowledge entry
+ */
+export interface KnowledgeEntryVersionEntity {
+  id: string;
+  entryId: string;
+  version: number;
+  title: string;
+  content: string;
+  summary: string | null;
+  createdAt: Date;
+  createdBy: string;
+  changeNote: string | null;
+}
+
+/**
+ * Version list item with author information
+ */
+export interface KnowledgeEntryVersionWithAuthor extends KnowledgeEntryVersionEntity {
+  author: {
+    id: string;
+    name: string;
+    email: string;
+  };
+}
+
+/**
+ * Paginated version list response
+ */
+export interface PaginatedVersions {
+  data: KnowledgeEntryVersionWithAuthor[];
+  pagination: {
+    page: number;
+    limit: number;
+    total: number;
+    totalPages: number;
+  };
+}