feat: remove unused plugin version comparison and types, refactor proxy server to support authentication

- Deleted version comparison logic from `pkg/plugin/sign/version.go`.
- Removed unused types and constants from `pkg/plugin/types.go`.
- Updated `pkg/protocol/message.go` to remove plugin-related message types.
- Enhanced `pkg/proxy/http.go` and `pkg/proxy/socks5.go` to include username/password authentication for HTTP and SOCKS5 proxies.
- Modified `pkg/proxy/server.go` to pass authentication parameters to server constructors.
- Added new API endpoint to generate installation commands with a token for clients.
- Created database functions to manage installation tokens in `internal/server/db/install_token.go`.
- Implemented the installation command generation logic in `internal/server/router/handler/install.go`.
- Updated web frontend to support installation command generation and display in `web/src/views/ClientsView.vue`.

pkg/proxy/http.go

@@ -2,6 +2,8 @@ package proxy
 
 import (
 	"bufio"
+	"encoding/base64"
+	"errors"
 	"io"
 	"net"
 	"net/http"
@@ -12,13 +14,15 @@ import (
 
 // HTTPServer HTTP 代理服务
 type HTTPServer struct {
-	dialer  Dialer
-	onStats func(in, out int64) // 流量统计回调
+	dialer   Dialer
+	onStats  func(in, out int64) // 流量统计回调
+	username string
+	password string
 }
 
 // NewHTTPServer 创建 HTTP 代理服务
-func NewHTTPServer(dialer Dialer, onStats func(in, out int64)) *HTTPServer {
-	return &HTTPServer{dialer: dialer, onStats: onStats}
+func NewHTTPServer(dialer Dialer, onStats func(in, out int64), username, password string) *HTTPServer {
+	return &HTTPServer{dialer: dialer, onStats: onStats, username: username, password: password}
 }
 
 // HandleConn 处理 HTTP 代理连接
@@ -31,12 +35,45 @@ func (h *HTTPServer) HandleConn(conn net.Conn) error {
 		return err
 	}
 
+	// 检查认证
+	if h.username != "" && h.password != "" {
+		if !h.checkAuth(req) {
+			conn.Write([]byte("HTTP/1.1 407 Proxy Authentication Required\r\nProxy-Authenticate: Basic realm=\"proxy\"\r\n\r\n"))
+			return errors.New("authentication required")
+		}
+	}
+
 	if req.Method == http.MethodConnect {
 		return h.handleConnect(conn, req)
 	}
 	return h.handleHTTP(conn, req, reader)
 }
 
+// checkAuth 检查 Proxy-Authorization 头
+func (h *HTTPServer) checkAuth(req *http.Request) bool {
+	auth := req.Header.Get("Proxy-Authorization")
+	if auth == "" {
+		return false
+	}
+
+	const prefix = "Basic "
+	if !strings.HasPrefix(auth, prefix) {
+		return false
+	}
+
+	decoded, err := base64.StdEncoding.DecodeString(auth[len(prefix):])
+	if err != nil {
+		return false
+	}
+
+	credentials := strings.SplitN(string(decoded), ":", 2)
+	if len(credentials) != 2 {
+		return false
+	}
+
+	return credentials[0] == h.username && credentials[1] == h.password
+}
+
 // handleConnect 处理 CONNECT 方法 (HTTPS)
 func (h *HTTPServer) handleConnect(conn net.Conn, req *http.Request) error {
 	target := req.Host