feat(rdp): 新增 RDP 远程桌面/SMB/账单同步能力 + 清理编译产物

主要变更：
- RDP 远程桌面：新增 backend/pkg/rdp（RDP 引擎 + credssp/display/rle/trace）、
  backend/controller/rdp*（连接/凭证/文件/会话/实时）、frontend RDP 组件与 API
- Windows SMB 文件传输：backend/pkg/winsmb
- 云账单同步：backend/pkg/billingsync + billing_sync/aliyun_billing，前端账单详情
- Agent CLI Kubernetes 工具：kubernetes_action/get、pod_execute/logs
- 服务器导入助手：server_import_helpers、ImportCredentialSettings
- 国际化与组件重构（cloud/deploy/monitor/server/system 等多模块）
- 清理编译产物二进制：移除 backend/server、backend/agent/bin/aiops-agent-*
- .gitignore：新增 backend/agent/ 与 .cache/（避免 334MB go-build 缓存误入库）

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

backend/controller/billing_sync.go

@@ -0,0 +1,85 @@
+package controller
+
+import (
+	"fmt"
+	"net/http"
+	"strconv"
+
+	"ezops/model"
+	"ezops/pkg/billingsync"
+
+	"github.com/gin-gonic/gin"
+)
+
+// syncBillingRequest 同步账单请求（可选指定账号） // Logan.Li
+type syncBillingRequest struct {
+	AccountID *uint  `json:"account_id"`
+	Date      string `json:"date"` // YYYY-MM-DD，默认昨日
+}
+
+// SyncYesterdayBillings 从云账号 AK 同步指定日期（默认昨日）账单 // Logan.Li
+// POST /cloud-billings/sync
+func (h *BillingHandler) SyncYesterdayBillings(c *gin.Context) {
+	var req syncBillingRequest
+	_ = c.ShouldBindJSON(&req)
+
+	billingDate := req.Date
+	if billingDate == "" {
+		billingDate = billingsync.Yesterday()
+	}
+	if len(billingDate) != 10 {
+		c.JSON(http.StatusBadRequest, model.Response{Code: 400, Message: "date 格式应为 YYYY-MM-DD"})
+		return
+	}
+
+	result := billingsync.SyncDate(h.db, billingDate, req.AccountID)
+	if result.Accounts == 0 {
+		c.JSON(http.StatusBadRequest, model.Response{Code: 400, Message: "没有可同步的活跃云账号，请先在云账号管理中添加 AK"})
+		return
+	}
+
+	msg := fmt.Sprintf("同步完成：新增 %d 条，更新 %d 条", result.Created, result.Updated)
+	if len(result.Errors) > 0 {
+		msg += fmt.Sprintf("，%d 个账号失败", len(result.Errors))
+	}
+
+	c.JSON(http.StatusOK, model.Response{
+		Code:    200,
+		Message: msg,
+		Data:    result,
+	})
+}
+
+// SyncAccountBilling 同步单个云账号账单
+// POST /cloud-accounts/:id/sync-billing
+func (h *BillingHandler) SyncAccountBilling(c *gin.Context) {
+	id, _ := strconv.Atoi(c.Param("id"))
+	if id <= 0 {
+		c.JSON(http.StatusBadRequest, model.Response{Code: 400, Message: "无效账号 ID"})
+		return
+	}
+
+	var req struct {
+		Date string `json:"date"`
+	}
+	_ = c.ShouldBindJSON(&req)
+
+	billingDate := req.Date
+	if billingDate == "" {
+		billingDate = billingsync.Yesterday()
+	}
+
+	uid := uint(id)
+	result := billingsync.SyncDate(h.db, billingDate, &uid)
+	if result.Accounts == 0 {
+		c.JSON(http.StatusNotFound, model.Response{Code: 404, Message: "云账号不存在或未激活"})
+		return
+	}
+
+	msg := fmt.Sprintf("同步完成：新增 %d 条，更新 %d 条", result.Created, result.Updated)
+	if len(result.Errors) > 0 {
+		msg = "同步失败: " + result.Errors[0]
+	}
+
+	c.JSON(http.StatusOK, model.Response{Code: 200, Message: msg, Data: result})
+}