refactor: 将 search_spu_products 重命名为 search_products

## 修改内容

### 1. Product Agent prompt
- 将工具名从 `search_spu_products` 改为 `search_products`
- 更新所有示例代码
- 保持功能说明不变（Mall API SPU 搜索）

### 2. Product Agent 代码
**文件**: agent/agents/product.py

**修改**:
- 第 24 行：工具名改为 `search_products`
- 第 65、77 行：示例中的工具名更新
- 第 219-230 行：注入逻辑改为检查 `search_products`
- 第 284 行：工具结果检查改为 `search_products`
- 第 279-333 行：变量名 `spu_products` → `products`
- 第 280 行：`has_spu_search_result` → `has_product_search_result`

### 3. Product MCP Server
**文件**: mcp_servers/product_mcp/server.py

**修改**:
- 第 292 行：函数名 `search_spu_products` → `search_products`
- 第 300 行：文档字符串更新
- 功能完全相同，只是重命名

### 4. 移除映射逻辑
- 移除了 `search_products` → `search_spu_products` 的工具名映射
- 保留了 `query` → `keyword` 的参数映射（向后兼容）

## 好处

1. **简化命名**：`search_products` 比 `search_spu_products` 更简洁
2. **统一接口**：与系统中其他搜索工具命名一致
3. **降低复杂度**：减少名称长度和冗余

## 向后兼容

参数映射保留：
```python
# 仍然支持旧参数名
{"query": "ring"} → {"keyword": "ring"}
```

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

agent/agents/product.py

@@ -21,7 +21,7 @@ PRODUCT_AGENT_PROMPT = """你是一个专业的 B2B 商品顾问助手。
 
 ## 可用工具
 
-1. **search_spu_products** - 搜索商品
+1. **search_products** - 搜索商品
    - keyword: 搜索关键词（商品名称、编号等）
    - page_size: 每页数量（默认 60，最大 100）
    - page: 页码（默认 1）
@@ -62,7 +62,7 @@ PRODUCT_AGENT_PROMPT = """你是一个专业的 B2B 商品顾问助手。
 ```json
 {
   "action": "call_tool",
-  "tool_name": "search_spu_products",
+  "tool_name": "search_products",
   "arguments": {
     "keyword": "ring"
   }
@@ -74,7 +74,7 @@ PRODUCT_AGENT_PROMPT = """你是一个专业的 B2B 商品顾问助手。
 ```json
 {
   "action": "call_tool",
-  "tool_name": "search_spu_products",
+  "tool_name": "search_products",
   "arguments": {
     "keyword": "手机"
   }
@@ -192,14 +192,6 @@ async def product_agent(state: AgentState) -> AgentState:
             tool_name = lines[0].strip()
             args_json = lines[1].strip() if len(lines) > 1 else '{}'
 
-            # Map old tool name to new tool name
-            if tool_name == "search_products":
-                tool_name = "search_spu_products"
-                logger.info(
-                    "Tool name mapped: search_products -> search_spu_products",
-                    conversation_id=state["conversation_id"]
-                )
-
             try:
                 arguments = json.loads(args_json) if args_json else {}
                 result = {
@@ -218,21 +210,13 @@ async def product_agent(state: AgentState) -> AgentState:
             # Standard JSON format
             result = json.loads(content)
 
-        # Auto-map search_products to search_spu_products in JSON format
-        if result.get("tool_name") == "search_products":
-            result["tool_name"] = "search_spu_products"
-            logger.info(
-                "Tool name mapped: search_products -> search_spu_products",
-                conversation_id=state["conversation_id"]
-            )
-
         action = result.get("action")
-        
+
         if action == "call_tool":
             arguments = result.get("arguments", {})
 
-            # Inject context for SPU product search (Mall API)
-            if result["tool_name"] == "search_spu_products":
+            # Inject context for product search (Mall API)
+            if result["tool_name"] == "search_products":
                 arguments["user_token"] = state.get("user_token")
                 arguments["user_id"] = state["user_id"]
                 arguments["account_id"] = state["account_id"]
@@ -292,25 +276,25 @@ async def product_agent(state: AgentState) -> AgentState:
 async def _generate_product_response(state: AgentState) -> AgentState:
     """Generate response based on product tool results"""
 
-    # 特殊处理：如果是 search_spu_products 工具返回，直接发送商品卡片
-    has_spu_search_result = False
-    spu_products = []
+    # 特殊处理：如果是 search_products 工具返回，直接发送商品卡片
+    has_product_search_result = False
+    products = []
 
     for result in state["tool_results"]:
-        if result["success"] and result["tool_name"] == "search_spu_products":
+        if result["success"] and result["tool_name"] == "search_products":
             data = result["data"]
             if isinstance(data, dict) and data.get("success"):
-                spu_products = data.get("products", [])
-                has_spu_search_result = True
+                products = data.get("products", [])
+                has_product_search_result = True
                 logger.info(
-                    "SPU product search results found",
-                    products_count=len(spu_products),
+                    "Product search results found",
+                    products_count=len(products),
                     keyword=data.get("keyword", "")
                 )
                 break
 
-    # 如果有 SPU 搜索结果，直接发送商品卡片
-    if has_spu_search_result and spu_products:
+    # 如果有商品搜索结果，直接发送商品卡片
+    if has_product_search_result and products:
         try:
             from integrations.chatwoot import ChatwootClient
             from core.language_detector import detect_language
@@ -325,14 +309,14 @@ async def _generate_product_response(state: AgentState) -> AgentState:
             if conversation_id:
                 await chatwoot.send_product_cards(
                     conversation_id=int(conversation_id),
-                    products=spu_products,
+                    products=products,
                     language=detected_language
                 )
 
                 logger.info(
                     "Product cards sent successfully",
                     conversation_id=conversation_id,
-                    products_count=len(spu_products),
+                    products_count=len(products),
                     language=detected_language
                 )
 
@@ -345,7 +329,7 @@ async def _generate_product_response(state: AgentState) -> AgentState:
             logger.error(
                 "Failed to send product cards, falling back to text response",
                 error=str(e),
-                products_count=len(spu_products)
+                products_count=len(products)
             )
 
     # 常规处理：生成文本响应