fix(v2): snapshot delete-dialog state before awaiting

The delete handler re-read the dialog refs (roms, platform, exclude flag)
after the request resolved. Because the dialog is a singleton, a fresh
showDeleteRomDialog event arriving mid-request could swap those refs, so
the completed request would prune the new dialog's IDs instead of the
ones it processed. Snapshot the state at entry and act on the snapshot.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: gantoine

frontend/src/v2/components/Dialogs/DeleteRomDialog.vue

@@ -75,18 +75,27 @@ async function deleteRoms() {
   if (deleting.value) return;
   deleting.value = true;
 
+  // Snapshot the dialog state up front: the dialog is a singleton, so a
+  // fresh `showDeleteRomDialog` event could replace these refs while the
+  // request is in flight. Acting on the snapshot keeps the response tied
+  // to the ROMs it actually processed.
+  const targetRoms = roms.value;
+  const targetPlatformId = platformId.value;
+  const deleteFromFs = romsToDeleteFromFs.value;
+  const exclude = excludeOnDelete.value;
+
   try {
     const response = await romApi.deleteRoms({
-      roms: roms.value,
-      deleteFromFs: romsToDeleteFromFs.value,
+      roms: targetRoms,
+      deleteFromFs,
     });
     // The backend deletes per-ROM and can partially fail; only prune the
     // ROMs it actually removed so a failed subset stays visible and
     // selected for the user to retry.
     const failedIds = new Set(response.data.failed_ids);
-    const deletedRoms = roms.value.filter((rom) => !failedIds.has(rom.id));
+    const deletedRoms = targetRoms.filter((rom) => !failedIds.has(rom.id));
     snackbar.success(
-      fsCount.value > 0
+      deleteFromFs.length > 0
         ? t("rom.deleted-from-filesystem", {
             count: response.data.successful_items,
           })
@@ -95,7 +104,7 @@ async function deleteRoms() {
           }),
       { icon: "mdi-check-bold" },
     );
-    if (excludeOnDelete.value) {
+    if (exclude) {
       for (const rom of deletedRoms) {
         const type = rom.has_simple_single_file
           ? "EXCLUDED_SINGLE_FILES"
@@ -131,7 +140,7 @@ async function deleteRoms() {
     if (route.name === "rom" && deletedRoms.length > 0) {
       router.push({
         name: ROUTES.PLATFORM,
-        params: { platform: platformId.value },
+        params: { platform: targetPlatformId },
       });
     }
   } catch (error: unknown) {