feat(export): 批量导出生成 Excel 后弹窗提示用户 (§17.24)

Excel 成功写入后弹出 QMessageBox，显示文件路径并引导切换
到「AI 穿搭」页直接使用；无有效印花子目录时不弹框。

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/widgets/queue_panel.py

@@ -395,13 +395,25 @@ class QueuePanel(QWidget):
 
         self._running = False
         self._batch_btn.setText("开始批量导出")
-        self._write_outfit_excel(run_dir)
+        excel_path = self._write_outfit_excel(run_dir)
+        if excel_path:
+            from PySide6.QtWidgets import QMessageBox
+            QMessageBox.information(
+                self,
+                "AI 穿搭 Excel 已生成",
+                "已生成 AI 穿搭 Excel 文件：\n{}\n\n可切换到「AI 穿搭」页，选择该文件直接开始生成穿搭图。".format(
+                    excel_path
+                ),
+            )
 
     def _write_outfit_excel(self, run_dir):
-        """Generate an AI-outfit source Excel alongside *run_dir* (docs/02 §6.12)."""
+        """Generate an AI-outfit source Excel alongside *run_dir* (docs/02 §6.12).
+
+        Returns the excel path string on success, None if skipped or failed.
+        """
         run_path = Path(run_dir)
         if not run_path.is_dir():
-            return
+            return None
         _img_exts = {".png", ".jpg", ".jpeg", ".webp", ".gif"}
         rows = []
         for subdir in sorted(run_path.iterdir(), key=lambda p: p.name.lower()):
@@ -410,12 +422,14 @@ class QueuePanel(QWidget):
             if any(f.suffix.lower() in _img_exts for f in subdir.iterdir() if f.is_file()):
                 rows.append((subdir.name, str(subdir) + os.sep))
         if not rows:
-            return
+            return None
         excel_path = run_path.with_suffix(".xlsx")
         try:
             write_outfit_source_excel(excel_path, rows)
+            return str(excel_path)
         except Exception as exc:
             logger.error("Failed to write outfit source Excel: %s", exc)
+            return None
 
     def _image_size(self, path):
         """Return (w, h) for path, caching within a run. None if unreadable."""