Fix UMAP visualization hanging on search

Fixed bug where searching caused canvas to hang and hover to stop working. The zoom behavior was re-initializing every time the filtered results changed, destroying the interaction state.

Changed zoom useEffect dependency from [filtered] to [] so it only initializes once on mount.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: benthecoder

components/KnowledgeMap.tsx

@@ -225,7 +225,7 @@ export default function KnowledgeMap({
       selection.on(".zoom", null);
       canvas.removeEventListener("wheel", preventScroll);
     };
-  }, [filtered]);
+  }, []);
 
   // Mouse hover
   const handleMouseMove = useCallback(