fix: code review cleanup - schema sync, type safety, null handling

- Sync KnowledgeLink schema with migration (add displayText, positionStart, positionEnd, resolved)
- Make targetId optional to support unresolved links
- Fix null handling in graph.service.ts (skip unresolved links)
- Add explicit types to frontend components (remove implicit any)
- Remove unused WikiLink import
- Add null-safe statusInfo check in EntryCard

apps/api/src/knowledge/services/link-resolution.service.ts

@@ -131,7 +131,9 @@ export class LinkResolutionService {
       return null;
     }
 
-    return fuzzyMatches[0].id;
+    // Return the single match
+    const match = fuzzyMatches[0];
+    return match ? match.id : null;
   }
 
   /**