refactor: userpreferences are now in the DB

prisma/migrations/20250916201629_add_user_preferences/migration.sql

@@ -0,0 +1,9 @@
+-- CreateTable
+CREATE TABLE "user_preferences" (
+    "id" TEXT NOT NULL PRIMARY KEY,
+    "kanbanFilters" JSONB,
+    "viewPreferences" JSONB,
+    "columnVisibility" JSONB,
+    "createdAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" DATETIME NOT NULL
+);