fix: resolve 7 audit issues - webhook tokens, cookie security, avatar save, TUI fallback, dead code, valkey default

internal/message/handlers.go

@@ -28,12 +28,6 @@ type Handler struct {
 	logger      *slog.Logger
 }
 
-type Handler_old struct {
-	db       *sql.DB
-	hub      *gateway.Hub
-	mentions *MentionHandler
-}
-
 func NewHandler(db *sql.DB, hub *gateway.Hub, pushHandler *push.Handler, logger *slog.Logger) *Handler {
 	return &Handler{
 		db:          db,