Remove legacy mode.

- Deleted the legacy WebSocket client implementation (`wstoclient.go`) and its test file (`wstoclient_test.go`).
- Removed legacy handling from the HTTP manager, including legacy proxy setup and routing.
- Cleaned up session management by removing legacy host checks and related functions.
- Eliminated the legacy WebRTC handler and its associated logic.
- Updated session interface to remove legacy methods.
- Removed legacy API documentation and configuration options from migration guide and help files.

server/internal/config/root.go

@@ -13,7 +13,6 @@ import (
 
 type Root struct {
 	Config string
-	Legacy bool
 
 	LogLevel   zerolog.Level
 	LogTime    string
@@ -34,14 +33,6 @@ func (Root) Init(cmd *cobra.Command) error {
 		return err
 	}
 
-	// whether legacy configs and api should be enabled.
-	// - if not specified, it will be automatically enabled if at least one legacy config entry is found.
-	// - if it is specified, it will be enabled/disabled regardless of the presence of legacy config entries.
-	cmd.PersistentFlags().Bool("legacy", true, "enable legacy mode")
-	if err := viper.BindPFlag("legacy", cmd.PersistentFlags().Lookup("legacy")); err != nil {
-		return err
-	}
-
 	cmd.PersistentFlags().String("log.level", "info", "set log level (trace, debug, info, warn, error, fatal, panic, disabled)")
 	if err := viper.BindPFlag("log.level", cmd.PersistentFlags().Lookup("log.level")); err != nil {
 		return err
@@ -81,10 +72,6 @@ func (Root) InitV2(cmd *cobra.Command) error {
 
 func (s *Root) Set() {
 	s.Config = viper.GetString("config")
-	s.Legacy = viper.GetBool("legacy")
-	if s.Legacy {
-		log.Info().Msg("legacy configuration is enabled")
-	}
 
 	logLevel := viper.GetString("log.level")
 	level, err := zerolog.ParseLevel(logLevel)
@@ -121,8 +108,6 @@ func (s *Root) Set() {
 }
 
 func (s *Root) SetV2() {
-	enableLegacy := false
-
 	if viper.IsSet("logs") {
 		if viper.GetBool("logs") {
 			logs := filepath.Join(".", "logs")
@@ -134,12 +119,5 @@ func (s *Root) SetV2() {
 			s.LogDir = ""
 		}
 		log.Warn().Msg("you are using v2 configuration 'NEKO_LOGS' which is deprecated, please use 'NEKO_LOG_DIR=/path/to/logs' instead")
-		enableLegacy = true
-	}
-
-	// set legacy flag if any V2 configuration was used
-	if !viper.IsSet("legacy") && enableLegacy {
-		log.Warn().Msg("legacy configuration is enabled because at least one V2 configuration was used, please migrate to V3 configuration, visit https://neko.m1k1o.net/docs/v3/migration-from-v2 for more details")
-		viper.Set("legacy", true)
 	}
 }