fix: 搜索走 SearXNG + 工具调用分页修复

- ai-core DevTools 启动配置补充 SEARXNG_URL，避免回退到 DuckDuckGo 导致超时
- 工具调用 API 加入 offset 分页，修复 page 参数不生效问题
- 响应新增 total_pages 字段，修复前端分页栏不渲染

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/ai-core/cmd/main.go

@@ -397,19 +397,25 @@ func main() {
 		if limit > 500 {
 			limit = 500
 		}
-		calls := toolRegistry.GetCallLogs(toolName, limit)
-		if calls == nil {
-			calls = []plgManager.CallLogRecord{}
-		}
-		page, _ := strconv.Atoi(r.URL.Query().Get("page"))
+			page, _ := strconv.Atoi(r.URL.Query().Get("page"))
 		if page < 1 {
 			page = 1
 		}
+		offset := (page - 1) * limit
+		calls, total := toolRegistry.GetCallLogs(toolName, limit, offset)
+		if calls == nil {
+			calls = []plgManager.CallLogRecord{}
+		}
+		totalPages := total / limit
+		if total%limit != 0 {
+			totalPages++
+		}
 		w.Header().Set("Content-Type", "application/json")
 		json.NewEncoder(w).Encode(map[string]interface{}{
-			"calls": calls, "total": len(calls), "page": page, "limit": limit,
+			"calls": calls, "total": total, "total_pages": totalPages,
+			"page": page, "limit": limit,
+		})
 		})
-	})
 
 	// 工具调用统计
 	mux.HandleFunc("/api/v1/tools/calls/stats", func(w http.ResponseWriter, r *http.Request) {