feat: Implement knowledge import feature for characters

- Added KnowledgeImport page for importing character knowledge from URLs.
- Integrated URL validation and error handling for unsupported websites.
- Created API endpoints for importing content from URLs and retrieving character knowledge.
- Enhanced VectorStoreService with logging and error handling for vector memory storage.
- Updated frontend to display knowledge sources and manage them effectively.
- Added support for fetching recent character knowledge as a fallback in similarity searches.
- Updated OpenAPI documentation to reflect new import functionality.

apps/backend/src/import/interfaces/index.ts

@@ -0,0 +1,2 @@
+export { IImportAdapter, ImportResult } from './import-adapter.interface';
+export { IWebScraper, WebScraperResult } from './web-scraper.interface';