feat: 添加 RustDesk 协议支持和项目文档

- 新增 RustDesk 模块，支持与 RustDesk 客户端连接
  - 实现会合服务器协议和 P2P 连接
  - 支持 NaCl 加密和密钥交换
  - 添加视频帧和 HID 事件适配器
- 添加 Protobuf 协议定义 (message.proto, rendezvous.proto)
- 新增完整项目文档
  - 各功能模块文档 (video, hid, msd, otg, webrtc 等)
  - hwcodec 和 RustDesk 协议技术报告
  - 系统架构和技术栈文档
- 更新 Web 前端 RustDesk 配置界面和 API

protos/rendezvous.proto

@@ -0,0 +1,197 @@
+syntax = "proto3";
+package hbb;
+
+message RegisterPeer {
+  string id = 1;
+  int32 serial = 2;
+}
+
+enum ConnType {
+  DEFAULT_CONN = 0;
+  FILE_TRANSFER = 1;
+  PORT_FORWARD = 2;
+  RDP = 3;
+  VIEW_CAMERA = 4;
+}
+
+message RegisterPeerResponse { bool request_pk = 2; }
+
+message PunchHoleRequest { 
+  string id = 1; 
+  NatType nat_type = 2;
+  string licence_key = 3;
+  ConnType conn_type = 4;
+  string token = 5;
+  string version = 6;
+}
+
+message PunchHole { 
+  bytes socket_addr = 1;
+  string relay_server = 2;
+  NatType nat_type = 3;
+}
+
+message TestNatRequest {
+  int32 serial = 1;
+}
+
+// per my test, uint/int has no difference in encoding, int not good for negative, use sint for negative
+message TestNatResponse {
+  int32 port = 1; 
+  ConfigUpdate cu = 2; // for mobile
+}
+
+enum NatType {
+  UNKNOWN_NAT = 0;
+  ASYMMETRIC = 1;
+  SYMMETRIC = 2;
+}
+
+message PunchHoleSent {
+  bytes socket_addr = 1;
+  string id = 2;
+  string relay_server = 3;
+  NatType nat_type = 4;
+  string version = 5;
+}
+
+message RegisterPk {
+  string id = 1;
+  bytes uuid = 2;
+  bytes pk = 3;
+  string old_id = 4;
+}
+
+message RegisterPkResponse {
+  enum Result {
+    OK = 0;
+    UUID_MISMATCH = 2;
+    ID_EXISTS = 3;
+    TOO_FREQUENT = 4;
+    INVALID_ID_FORMAT = 5;
+    NOT_SUPPORT = 6;
+    SERVER_ERROR = 7;
+  }
+  Result result = 1;
+  int32 keep_alive = 2;
+}
+
+message PunchHoleResponse {
+  bytes socket_addr = 1;
+  bytes pk = 2;
+  enum Failure {
+    ID_NOT_EXIST = 0;
+    OFFLINE = 2;
+    LICENSE_MISMATCH = 3;
+    LICENSE_OVERUSE = 4;
+  }
+  Failure failure = 3;
+  string relay_server = 4;
+  oneof union {
+    NatType nat_type = 5;
+    bool is_local = 6;
+  }
+  string other_failure = 7;
+  int32 feedback = 8;
+}
+
+message ConfigUpdate {
+  int32 serial = 1;
+  repeated string rendezvous_servers = 2;
+}
+
+message RequestRelay {
+  string id = 1;
+  string uuid = 2;
+  bytes socket_addr = 3;
+  string relay_server = 4;
+  bool secure = 5;
+  string licence_key = 6;
+  ConnType conn_type = 7;
+  string token = 8;
+}
+
+message RelayResponse {
+  bytes socket_addr = 1;
+  string uuid = 2;
+  string relay_server = 3;
+  oneof union {
+    string id = 4;
+    bytes pk = 5;
+  }
+  string refuse_reason = 6;
+  string version = 7;
+  int32 feedback = 9;
+}
+
+message SoftwareUpdate { string url = 1; }
+
+// if in same intranet, punch hole won't work both for udp and tcp,
+// even some router has below connection error if we connect itself,
+//  { kind: Other, error: "could not resolve to any address" },
+// so we request local address to connect.
+message FetchLocalAddr { 
+  bytes socket_addr = 1; 
+  string relay_server = 2;
+}
+
+message LocalAddr {
+  bytes socket_addr = 1;
+  bytes local_addr = 2;
+  string relay_server = 3;
+  string id = 4;
+  string version = 5;
+}
+
+message PeerDiscovery {
+  string cmd = 1;
+  string mac = 2;
+  string id = 3;
+  string username = 4;
+  string hostname = 5;
+  string platform = 6;
+  string misc = 7;
+}
+
+message OnlineRequest {
+  string id = 1;
+  repeated string peers = 2;
+}
+
+message OnlineResponse {
+  bytes states = 1;
+}
+
+message KeyExchange {
+  repeated bytes keys = 1; 
+}
+
+message HealthCheck {
+  string token = 1;
+}
+
+message RendezvousMessage {
+  oneof union {
+    RegisterPeer register_peer = 6;
+    RegisterPeerResponse register_peer_response = 7;
+    PunchHoleRequest punch_hole_request = 8;
+    PunchHole punch_hole = 9;
+    PunchHoleSent punch_hole_sent = 10;
+    PunchHoleResponse punch_hole_response = 11;
+    FetchLocalAddr fetch_local_addr = 12;
+    LocalAddr local_addr = 13;
+    ConfigUpdate configure_update = 14;
+    RegisterPk register_pk = 15;
+    RegisterPkResponse register_pk_response = 16;
+    SoftwareUpdate software_update = 17;
+    RequestRelay request_relay = 18;
+    RelayResponse relay_response = 19;
+    TestNatRequest test_nat_request = 20;
+    TestNatResponse test_nat_response = 21;
+    PeerDiscovery peer_discovery = 22;
+    OnlineRequest online_request = 23;
+    OnlineResponse online_response = 24;
+    KeyExchange key_exchange = 25;
+    HealthCheck hc = 26;
+  }
+}