feat: 添加IP竞速拨号器与IP偏好设置，连接状态显示域名与实际IP

- 新增竞速拨号器(racedial.go)：域名连接时并行解析所有A/AAAA记录，
  同时对所有IP发起TCP连接，第一个成功的胜出，确保选择延迟最低的地址
- ServerProfile新增IPPreference字段(auto/v4/v6)，支持用户指定IP版本偏好
- 填写服务器IP时跳过域名解析直接使用IP，顺序failover
- 连接成功后状态栏显示「已连接 (域名 -> 实际IP)」
- DB迁移v6：server_profiles表添加ip_preference列
- WebSocket拨号与HTTP登录均使用竞速拨号器
- 补充中英文i18n翻译

internal/db/db.go

@@ -55,7 +55,10 @@ func (s *Store) migrate() error {
 	if err := s.migrateV4(); err != nil {
 		return err
 	}
-	return s.migrateV5()
+	if err := s.migrateV5(); err != nil {
+		return err
+	}
+	return s.migrateV6()
 }
 
 func (s *Store) migrateV2() error {
@@ -290,6 +293,20 @@ func (s *Store) migrateV5() error {
 	return nil
 }
 
+// migrateV6 adds the ip_preference column to server_profiles for
+// controlling IPv4/IPv6 address selection when connecting by hostname.
+// Idempotent: skips if the column already exists.
+func (s *Store) migrateV6() error {
+	if columnExists(s.db, "server_profiles", "ip_preference") {
+		return nil
+	}
+	_, err := s.db.Exec(`ALTER TABLE server_profiles ADD COLUMN ip_preference TEXT NOT NULL DEFAULT 'auto'`)
+	if err != nil {
+		return fmt.Errorf("migrate v6 add ip_preference: %w", err)
+	}
+	return nil
+}
+
 // splitCIDRsByFamily splits a comma-separated CIDR string into IPv4 and
 // IPv6 parts. Used for migration from the old custom_cidrs column.
 func splitCIDRsByFamily(customCIDRs string) (v4, v6 string) {
@@ -354,6 +371,7 @@ CREATE TABLE IF NOT EXISTS server_profiles (
 	cidr_v6_urls    TEXT    NOT NULL DEFAULT '',
 	mtu_override    INTEGER NOT NULL DEFAULT 0,
 	auto_connect    INTEGER NOT NULL DEFAULT 0,
+	ip_preference   TEXT    NOT NULL DEFAULT 'auto',
 	created_at      DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
 	last_connected_at DATETIME
 );

internal/db/profile.go

@@ -16,13 +16,15 @@ func (s *Store) CreateProfile(p *model.ServerProfile) (int64, error) {
 		    username, auth_mode, routing_mode,
 		    cidr_v4, cidr_v6, cidr_v4_urls, cidr_v6_urls,
 		    mtu_override, auto_connect,
-		    tls_ca_cert, tls_ca_path, tls_insecure, tls_pinned_hash)
-		 VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`,
+		    tls_ca_cert, tls_ca_path, tls_insecure, tls_pinned_hash,
+		    ip_preference)
+		 VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)`,
 		p.Name, p.Protocol, p.Host, p.ServerIPs, p.Port, p.Path,
 		p.Username, p.AuthMode, p.RoutingMode,
 		p.CIDRV4, p.CIDRV6, p.CIDRV4URLs, p.CIDRV6URLs,
 		p.MTUOverride, p.AutoConnect,
 		p.TLSCACert, p.TLSCAPath, p.TLSInsecure, p.TLSPinnedHash,
+		p.IPPreference,
 	)
 	if err != nil {
 		return 0, fmt.Errorf("insert profile: %w", err)
@@ -43,6 +45,7 @@ func (s *Store) GetProfile(id int64) (*model.ServerProfile, error) {
 		        cidr_v4, cidr_v6, cidr_v4_urls, cidr_v6_urls,
 		        mtu_override, auto_connect,
 		        tls_ca_cert, tls_ca_path, tls_insecure, tls_pinned_hash,
+		        ip_preference,
 		        created_at, last_connected_at
 		 FROM server_profiles WHERE id = ?`, id,
 	).Scan(&p.ID, &p.Name, &p.Protocol, &p.Host, &p.ServerIPs, &p.Port, &p.Path,
@@ -50,7 +53,7 @@ func (s *Store) GetProfile(id int64) (*model.ServerProfile, error) {
 		&p.CIDRV4, &p.CIDRV6, &p.CIDRV4URLs, &p.CIDRV6URLs,
 		&p.MTUOverride, &p.AutoConnect,
 		&p.TLSCACert, &p.TLSCAPath, &p.TLSInsecure, &p.TLSPinnedHash,
-		&p.CreatedAt, &last)
+		&p.IPPreference, &p.CreatedAt, &last)
 	if err != nil {
 		return nil, fmt.Errorf("get profile %d: %w", id, err)
 	}
@@ -68,6 +71,7 @@ func (s *Store) ListProfiles() ([]model.ServerProfile, error) {
 		        cidr_v4, cidr_v6, cidr_v4_urls, cidr_v6_urls,
 		        mtu_override, auto_connect,
 		        tls_ca_cert, tls_ca_path, tls_insecure, tls_pinned_hash,
+		        ip_preference,
 		        created_at, last_connected_at
 		 FROM server_profiles ORDER BY name`)
 	if err != nil {
@@ -84,7 +88,7 @@ func (s *Store) ListProfiles() ([]model.ServerProfile, error) {
 			&p.CIDRV4, &p.CIDRV6, &p.CIDRV4URLs, &p.CIDRV6URLs,
 			&p.MTUOverride, &p.AutoConnect,
 			&p.TLSCACert, &p.TLSCAPath, &p.TLSInsecure, &p.TLSPinnedHash,
-			&p.CreatedAt, &last); err != nil {
+			&p.IPPreference, &p.CreatedAt, &last); err != nil {
 			return nil, err
 		}
 		if last.Valid {
@@ -103,13 +107,15 @@ func (s *Store) UpdateProfile(p *model.ServerProfile) error {
 		    username = ?, auth_mode = ?, routing_mode = ?,
 		    cidr_v4 = ?, cidr_v6 = ?, cidr_v4_urls = ?, cidr_v6_urls = ?,
 		    mtu_override = ?, auto_connect = ?,
-		    tls_ca_cert = ?, tls_ca_path = ?, tls_insecure = ?, tls_pinned_hash = ?
+		    tls_ca_cert = ?, tls_ca_path = ?, tls_insecure = ?, tls_pinned_hash = ?,
+		    ip_preference = ?
 		 WHERE id = ?`,
 		p.Name, p.Protocol, p.Host, p.ServerIPs, p.Port, p.Path,
 		p.Username, p.AuthMode, p.RoutingMode,
 		p.CIDRV4, p.CIDRV6, p.CIDRV4URLs, p.CIDRV6URLs,
 		p.MTUOverride, p.AutoConnect,
-		p.TLSCACert, p.TLSCAPath, p.TLSInsecure, p.TLSPinnedHash, p.ID)
+		p.TLSCACert, p.TLSCAPath, p.TLSInsecure, p.TLSPinnedHash,
+		p.IPPreference, p.ID)
 	if err != nil {
 		return fmt.Errorf("update profile %d: %w", p.ID, err)
 	}