fix(db): add missing Label.type and UserAISettings.autoSave columns

These columns exist in schema.prisma but were never added via migration,
causing PrismaClientKnownRequestError on notebook/label queries in production.
Uses idempotent DO 4109514 IF NOT EXISTS 4109514 blocks to be safe on any DB state.

memento-note/prisma/migrations/20260509160000_add_missing_columns/migration.sql

@@ -0,0 +1,24 @@
+-- Migration de rattrapage : colonnes présentes dans schema.prisma mais absentes de la DB
+-- Label.type et UserAISettings.autoSave n'avaient pas de migration correspondante
+
+-- AlterTable Label — ajoute la colonne type si elle n'existe pas déjà
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns
+    WHERE table_name = 'Label' AND column_name = 'type'
+  ) THEN
+    ALTER TABLE "Label" ADD COLUMN "type" TEXT NOT NULL DEFAULT 'user';
+  END IF;
+END $$;
+
+-- AlterTable UserAISettings — ajoute autoSave si elle n'existe pas déjà
+DO $$
+BEGIN
+  IF NOT EXISTS (
+    SELECT 1 FROM information_schema.columns
+    WHERE table_name = 'UserAISettings' AND column_name = 'autoSave'
+  ) THEN
+    ALTER TABLE "UserAISettings" ADD COLUMN "autoSave" BOOLEAN NOT NULL DEFAULT true;
+  END IF;
+END $$;