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`.

internal/server/db/install_token.go

@@ -0,0 +1,45 @@
+package db
+
+// CreateInstallToken 创建安装token
+func (s *SQLiteStore) CreateInstallToken(token *InstallToken) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	_, err := s.db.Exec(`INSERT INTO install_tokens (token, client_id, created_at, used) VALUES (?, ?, ?, ?)`,
+		token.Token, token.ClientID, token.CreatedAt, 0)
+	return err
+}
+
+// GetInstallToken 获取安装token
+func (s *SQLiteStore) GetInstallToken(token string) (*InstallToken, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var t InstallToken
+	var used int
+	err := s.db.QueryRow(`SELECT token, client_id, created_at, used FROM install_tokens WHERE token = ?`, token).
+		Scan(&t.Token, &t.ClientID, &t.CreatedAt, &used)
+	if err != nil {
+		return nil, err
+	}
+	t.Used = used == 1
+	return &t, nil
+}
+
+// MarkTokenUsed 标记token已使用
+func (s *SQLiteStore) MarkTokenUsed(token string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	_, err := s.db.Exec(`UPDATE install_tokens SET used = 1 WHERE token = ?`, token)
+	return err
+}
+
+// DeleteExpiredTokens 删除过期token
+func (s *SQLiteStore) DeleteExpiredTokens(expireTime int64) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	_, err := s.db.Exec(`DELETE FROM install_tokens WHERE created_at < ?`, expireTime)
+	return err
+}