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/services/config_service.py

@@ -33,8 +33,8 @@ _OUTFIT_PROMPT_FILENAME = "outfit_prompt.txt"
 
 # Default outfit prompt (docs/11 §7). Persisted to outfit_prompt.txt on first save.
 DEFAULT_OUTFIT_PROMPT = (
-    "为商品「{title}」（货号 {product_id}）生成人物上身实穿效果图：真人模特正面"
-    "穿着这件衣服，完整保留款式、版型、颜色与印花图案，自然光、纯色棚拍背景，"
+    "为商品「{title}」生成人物上身实穿效果图：真人模特正面穿着这件衣服，"
+    "完整保留款式、版型、颜色与印花图案，自然光、纯色棚拍背景，"
     "电商主图风格，不加文字与促销标签。"
 )