drop is folder column useless

backend/internal/db/migrations/006_folders.down.sql

@@ -0,0 +1 @@
+ALTER TABLE files ADD COLUMN is_folder BOOLEAN NOT NULL DEFAULT false;

backend/internal/db/migrations/006_folders.up.sql

@@ -0,0 +1,2 @@
+-- VaultDrop 003: tags table
+ALTER TABLE files DROP COLUMN IF EXISTS is_folder;