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/pkg/rdp/transport/x224.go

@@ -0,0 +1,119 @@
+package transport
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+const (
+	x224TypeConnectionRequest = 0xE0
+	x224TypeConnectionConfirm = 0xD0
+	x224TypeData              = 0xF0
+
+	negTypeRequest  = 0x01
+	negTypeResponse = 0x02
+	negTypeFailure  = 0x03
+
+	protocolSSL     = 0x00000001
+	protocolCredSSP = 0x00000002
+)
+
+const (
+	ProtocolStandard uint32 = 0
+	ProtocolTLS      uint32 = protocolSSL
+	ProtocolCredSSP  uint32 = protocolCredSSP
+)
+
+// NegotiationResult 是 X.224 阶段的 RDP 安全协议协商结果 // Logan.Li
+type NegotiationResult struct {
+	SelectedProtocol uint32
+	FailureCode      uint32
+}
+
+func (r NegotiationResult) ProtocolName() string {
+	switch r.SelectedProtocol {
+	case ProtocolCredSSP:
+		return "CredSSP/NLA"
+	case ProtocolTLS:
+		return "TLS"
+	case ProtocolStandard:
+		return "Standard RDP"
+	default:
+		return fmt.Sprintf("unknown(0x%x)", r.SelectedProtocol)
+	}
+}
+
+// BuildConnectionRequest 构造 X.224 Connection Request，并请求 NLA/TLS 协商 // Logan.Li
+func BuildConnectionRequest() []byte {
+	return BuildConnectionRequestWithCookie("aiops")
+}
+
+// BuildConnectionRequestWithCookie 按 MS-RDPBCGR 2.2.1.1.1 构造包含 mstshash 的请求 // Logan.Li
+func BuildConnectionRequestWithCookie(username string) []byte {
+	if username == "" {
+		username = "aiops"
+	}
+	if len(username) > 9 {
+		username = username[:9]
+	}
+	cookie := []byte("Cookie: mstshash=" + username + "\r\n")
+	neg := make([]byte, 8)
+	neg[0] = negTypeRequest
+	neg[1] = 0
+	binary.LittleEndian.PutUint16(neg[2:4], uint16(len(neg)))
+	binary.LittleEndian.PutUint32(neg[4:8], protocolSSL|protocolCredSSP)
+
+	length := 7 + len(cookie) + len(neg)
+	pdu := make([]byte, 0, length)
+	pdu = append(pdu, byte(length-1))
+	pdu = append(pdu, x224TypeConnectionRequest)
+	pdu = append(pdu, 0x00, 0x00) // dst-ref // Logan.Li
+	pdu = append(pdu, 0x00, 0x00) // src-ref // Logan.Li
+	pdu = append(pdu, 0x00)       // class/options // Logan.Li
+	pdu = append(pdu, cookie...)
+	pdu = append(pdu, neg...)
+	return pdu
+}
+
+// ParseConnectionConfirm 解析 X.224 Connection Confirm 与 RDP Negotiation Response // Logan.Li
+func ParseConnectionConfirm(payload []byte) (NegotiationResult, error) {
+	if len(payload) < 7 {
+		return NegotiationResult{}, fmt.Errorf("short X.224 confirm: %d", len(payload))
+	}
+	if payload[1] != x224TypeConnectionConfirm {
+		return NegotiationResult{}, fmt.Errorf("unexpected X.224 pdu type: 0x%x", payload[1])
+	}
+	for i := 7; i+8 <= len(payload); i++ {
+		switch payload[i] {
+		case negTypeResponse:
+			return NegotiationResult{SelectedProtocol: binary.LittleEndian.Uint32(payload[i+4 : i+8])}, nil
+		case negTypeFailure:
+			return NegotiationResult{FailureCode: binary.LittleEndian.Uint32(payload[i+4 : i+8])}, fmt.Errorf("RDP negotiation failure: 0x%x", binary.LittleEndian.Uint32(payload[i+4:i+8]))
+		}
+	}
+	return NegotiationResult{SelectedProtocol: 0}, nil
+}
+
+// WriteX224Data 写入 X.224 Data TPDU，NLA 后的 MCS/GCC 数据仍经由该层承载 // Logan.Li
+func WriteX224Data(w io.Writer, payload []byte) error {
+	data := make([]byte, 0, len(payload)+3)
+	data = append(data, 0x02, x224TypeData, 0x80)
+	data = append(data, payload...)
+	return WriteTPKT(w, data)
+}
+
+// ReadX224Data 读取并剥离 X.224 Data TPDU 头，返回上层 MCS 负载 // Logan.Li
+func ReadX224Data(r io.Reader) ([]byte, error) {
+	payload, err := ReadTPKT(r)
+	if err != nil {
+		return nil, err
+	}
+	if len(payload) < 3 {
+		return nil, fmt.Errorf("X.224 data too short: %d", len(payload))
+	}
+	if payload[1] != x224TypeData {
+		return nil, fmt.Errorf("unexpected X.224 type: 0x%x", payload[1])
+	}
+	return payload[3:], nil
+}