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
+);

prisma/schema.prisma

@@ -84,3 +84,21 @@ model DailyCheckbox {
   @@index([date])
   @@map("daily_checkboxes")
 }
+
+model UserPreferences {
+  id String @id @default(cuid())
+  
+  // Filtres Kanban (JSON)
+  kanbanFilters Json?
+  
+  // Préférences de vue (JSON)
+  viewPreferences Json?
+  
+  // Visibilité des colonnes (JSON)
+  columnVisibility Json?
+  
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+  
+  @@map("user_preferences")
+}