Automatically select added files (#4325)

# Description of Changes
When adding files, the user probably wants to use them straight away in
the next tool that they use, so automatically select any added files (in
addition to whatever they previously had selected).

frontend/src/hooks/useFileHandler.ts

@@ -9,12 +9,12 @@ export const useFileHandler = () => {
 
   const addToActiveFiles = useCallback(async (file: File) => {
     // Let FileContext handle deduplication with quickKey logic
-    await actions.addFiles([file]);
+    await actions.addFiles([file], { selectFiles: true });
   }, [actions.addFiles]);
 
   const addMultipleFiles = useCallback(async (files: File[]) => {
     // Let FileContext handle deduplication with quickKey logic
-    await actions.addFiles(files);
+    await actions.addFiles(files, { selectFiles: true });
   }, [actions.addFiles]);
 
   // Add stored files preserving their original IDs to prevent session duplicates
@@ -25,7 +25,7 @@ export const useFileHandler = () => {
     });
 
     if (newFiles.length > 0) {
-      await actions.addStoredFiles(newFiles);
+      await actions.addStoredFiles(newFiles, { selectFiles: true });
     }
 
     console.log(`📁 Added ${newFiles.length} stored files (${filesWithMetadata.length - newFiles.length} skipped as duplicates)`);