Fix pattern re-upload after deletion by preserving filename

Fix bug where deleting a cached pattern prevented re-uploading because
the filename was lost. After deletion, the pattern remains visible in
the UI for re-editing and re-uploading, but the upload would silently
fail because displayFileName was empty.

The issue occurred because:
1. Pattern loaded from cache uses resumeFileName (from hook)
2. Local fileName state in FileUpload was never set (empty string)
3. After deletion, resumeFileName is cleared to null
4. displayFileName becomes empty, preventing upload

Solution:
- Add fallback to 'pattern.pes' when pesDataProp exists but no filename
- This ensures re-upload works after deletion while keeping pattern visible
- Pattern data (pesData) persists in App.tsx state for re-editing

Now users can delete a cached pattern and immediately re-upload it
with position adjustments or other modifications.

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/components/FileUpload.tsx

@@ -39,7 +39,8 @@ export function FileUpload({
 
   // Use prop pesData if available (from cached pattern), otherwise use local state
   const pesData = pesDataProp || localPesData;
-  const displayFileName = resumeFileName || fileName;
+  // When resumeFileName is cleared but we still have pesData, preserve the filename
+  const displayFileName = resumeFileName || fileName || (pesDataProp ? 'pattern.pes' : '');
   const [isLoading, setIsLoading] = useState(false);
 
   const handleFileChange = useCallback(

src/hooks/useBrotherMachine.ts

@@ -306,6 +306,7 @@ export function useBrotherMachine() {
       setResumeFileName(null);
       // NOTE: We intentionally DON'T clear setResumedPattern(null)
       // so the pattern remains visible in the canvas for re-editing
+      // However, we DO need to preserve pesData in App.tsx for re-upload
 
       await refreshStatus();
     } catch (err) {