fix: resolve golangci-lint issues in channel system

pkg/channels/manager.go

@@ -153,7 +153,7 @@ func (m *Manager) initChannel(name, displayName string) {
 			}
 		}
 		// Inject PlaceholderRecorder if channel supports it
-		if setter, ok := ch.(interface{ SetPlaceholderRecorder(PlaceholderRecorder) }); ok {
+		if setter, ok := ch.(interface{ SetPlaceholderRecorder(r PlaceholderRecorder) }); ok {
 			setter.SetPlaceholderRecorder(m)
 		}
 		m.channels[name] = ch

pkg/channels/pico/protocol.go

@@ -4,12 +4,12 @@ import "time"
 
 // Protocol message types.
 const (
-	// Client → Server
+	// TypeMessageSend is sent from client to server.
 	TypeMessageSend = "message.send"
 	TypeMediaSend   = "media.send"
 	TypePing        = "ping"
 
-	// Server → Client
+	// TypeMessageCreate is sent from server to client.
 	TypeMessageCreate = "message.create"
 	TypeMessageUpdate = "message.update"
 	TypeMediaCreate   = "media.create"