feat(ai-outfit): drop product_id from prompt UI + default template

Match the doc change (8a4ebe6): remove the 插入货号 button (keep only
插入标题) and drop 货号 {product_id} from DEFAULT_OUTFIT_PROMPT. product_id
still drives Excel column B and the output filename, not the AI prompt.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/widgets/ai_outfit_panel.py

@@ -258,10 +258,10 @@ class AiOutfitPanel(QWidget):
         self._prompt_edit.setFixedHeight(130)
         pv.addWidget(self._prompt_edit)
         prow = QHBoxLayout()
-        for text, ph in (("插入标题", "{title}"), ("插入货号", "{product_id}")):
-            b = QPushButton(text)
-            b.clicked.connect(lambda _=False, p=ph: self._prompt_edit.insertPlainText(p))
-            prow.addWidget(b)
+        insert_title_btn = QPushButton("插入标题")
+        insert_title_btn.clicked.connect(
+            lambda: self._prompt_edit.insertPlainText("{title}"))
+        prow.addWidget(insert_title_btn)
         preview_btn = QPushButton("预览最终提示词")
         preview_btn.clicked.connect(self._preview_prompt)
         prow.addWidget(preview_btn)