feat: 行为管理改为注册模式 - handlers接口返回已注册handler列表

- AdminProductActionController: 新增 GET /handlers 返回后端已注册的ActionHandler列表
- ActionHandlerRegistry: 新增 getHandlers() 方法暴露所有handler
- 行为管理只能注册后端已有handler的行为，不可随意创建

src/main/java/com/cool/modules/product/action/ActionHandlerRegistry.java

@@ -33,4 +33,8 @@ public class ActionHandlerRegistry {
     public boolean hasHandler(String actionCode) {
         return handlerMap.containsKey(actionCode);
     }
+
+    public List<ActionHandler> getHandlers() {
+        return handlers;
+    }
 }

src/main/java/com/cool/modules/product/controller/admin/AdminProductActionController.java

@@ -3,19 +3,38 @@ package com.cool.modules.product.controller.admin;
 import cn.hutool.json.JSONObject;
 import com.cool.core.annotation.CoolRestController;
 import com.cool.core.base.BaseController;
+import com.cool.core.request.R;
+import com.cool.modules.product.action.ActionHandler;
+import com.cool.modules.product.action.ActionHandlerRegistry;
 import com.cool.modules.product.entity.ProductActionEntity;
 import com.cool.modules.product.service.ProductActionService;
+import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.servlet.http.HttpServletRequest;
 import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.GetMapping;
+
+import java.util.List;
+import java.util.Map;
 
 @RequiredArgsConstructor
 @Tag(name = "商品行为管理", description = "商品行为管理")
 @CoolRestController(api = {"add", "delete", "update", "page", "info"})
 public class AdminProductActionController extends BaseController<ProductActionService, ProductActionEntity> {
 
+    private final ActionHandlerRegistry actionHandlerRegistry;
+
     @Override
     protected void init(HttpServletRequest request, JSONObject requestParams) {
         setPageOption(createOp());
     }
+
+    @Operation(summary = "获取已注册的行为处理器列表")
+    @GetMapping("/handlers")
+    public R handlers() {
+        List<Map<String, String>> handlers = actionHandlerRegistry.getHandlers().stream()
+                .map(h -> Map.of("code", h.getCode(), "name", h.getCode()))
+                .toList();
+        return R.ok(handlers);
+    }
 }