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/server_import_helpers.go

@@ -0,0 +1,85 @@
+package controller
+
+import (
+	"fmt"
+	"strings"
+
+	"ezops/model"
+	"ezops/pkg/crypto"
+
+	"gorm.io/gorm"
+)
+
+func (h *ServerHandler) loadImportCredential(id *uint, wantType string) (model.Credential, string, bool, error) {
+	return loadImportCredentialByDB(h.db, h.crypt, id, wantType)
+}
+
+func (h *CloudSyncHandler) loadImportCredential(id *uint, wantType string) (model.Credential, string, bool, error) {
+	return loadImportCredentialByDB(h.db, h.crypt, id, wantType)
+}
+
+func loadImportCredentialByDB(db *gorm.DB, crypt *crypto.SecretBox, id *uint, wantType string) (model.Credential, string, bool, error) {
+	var cred model.Credential
+	if id == nil || *id == 0 {
+		return cred, "", false, nil
+	}
+	if err := db.First(&cred, *id).Error; err != nil {
+		return cred, "", false, fmt.Errorf("凭据不存在")
+	}
+	if cred.SecretType != wantType {
+		return cred, "", false, fmt.Errorf("请选择 %s 类型凭据", strings.ToUpper(wantType))
+	}
+	plain, err := crypt.Decrypt(cred.Content)
+	if err != nil {
+		return cred, "", false, fmt.Errorf("凭据解密失败")
+	}
+	return cred, plain, true, nil
+}
+
+func normalizeImportOSType(osType, osName string) string {
+	raw := strings.ToLower(strings.TrimSpace(osType + " " + osName))
+	if strings.Contains(raw, "windows") || strings.Contains(raw, "win") {
+		return "windows"
+	}
+	return "linux"
+}
+
+// normalizeServerRemoteAccess 补齐历史导入数据中缺失的 os_type/protocol 字段 // Logan.Li
+func normalizeServerRemoteAccess(server *model.Server) {
+	if server == nil {
+		return
+	}
+	if server.OSType != "" && server.Protocol != "" {
+		if server.OSType == "windows" && server.Protocol != "rdp" {
+			server.Protocol = "rdp"
+		}
+		if server.Protocol == "rdp" && server.OSType == "" {
+			server.OSType = "windows"
+		}
+		if server.RDPPort == 0 {
+			server.RDPPort = 3389
+		}
+		return
+	}
+	osType := normalizeImportOSType(server.OSType, server.OS)
+	if osType == "windows" {
+		server.OSType = "windows"
+		server.Protocol = "rdp"
+		if server.RDPPort == 0 {
+			server.RDPPort = 3389
+		}
+		return
+	}
+	if server.OSType == "" {
+		server.OSType = "linux"
+	}
+	if server.Protocol == "" {
+		server.Protocol = "ssh"
+	}
+}
+
+// isRDPServer 判断资产是否应走 RDP 图形会话 // Logan.Li
+func isRDPServer(server model.Server) bool {
+	normalizeServerRemoteAccess(&server)
+	return server.Protocol == "rdp" || server.OSType == "windows"
+}