feat(tunnel): switch to yamux stream proxying and connection pooling

- Introduce pooled tunnel sessions (TunnelID/DataConnect) on client/server
- Proxy HTTP/HTTPS via raw HTTP over yamux streams; pipe TCP streams directly
- Move UI/stats into internal/shared; refactor CLI tunnel helpers; drop msgpack/hpack legacy

internal/client/cli/stop.go

@@ -28,7 +28,7 @@ func init() {
 	rootCmd.AddCommand(stopCmd)
 }
 
-func runStop(cmd *cobra.Command, args []string) error {
+func runStop(_ *cobra.Command, args []string) error {
 	if args[0] == "all" {
 		return stopAllDaemons()
 	}