Fix: FileTree scrolling - use h-full instead of flex-1

- FileTree had flex-1 inside an overflow container which didn't work
- Changed to h-full to properly fill the parent container height
- Scrolling now works correctly in the file tree area

gadget-code/frontend/src/components/FileTree.tsx

@@ -166,7 +166,7 @@ export default function FileTree({ workspaceMode, onFileSelect }: FileTreeProps)
   const rootLoading = state.loadingPaths.has('');
 
   return (
-    <div className="flex-1 overflow-auto p-2">
+    <div className="overflow-auto p-2 h-full">
       {rootLoading && (
         <div className="flex items-center justify-center py-8">
           <div className="animate-spin rounded-full h-6 w-6 border-b-2 border-brand"></div>