feat: enhance user preferences management with userId integration

- Added `userId` field to `UserPreferences` model in Prisma schema for user-specific preferences.
- Implemented migration to populate existing preferences with the first user.
- Updated user preferences service methods to handle user-specific data retrieval and updates.
- Modified API routes and components to ensure user authentication and fetch preferences based on the authenticated user.
- Enhanced session management in various components to load user preferences accordingly.

prisma/schema.prisma

@@ -20,6 +20,7 @@ model User {
   password    String   // Hashé avec bcrypt
   createdAt   DateTime @default(now())
   updatedAt   DateTime @updatedAt
+  preferences UserPreferences?
 
   @@map("users")
 }
@@ -101,6 +102,7 @@ model DailyCheckbox {
 
 model UserPreferences {
   id               String   @id @default(cuid())
+  userId           String   @unique
   kanbanFilters    Json?
   viewPreferences  Json?
   columnVisibility Json?
@@ -112,6 +114,7 @@ model UserPreferences {
   tfsSyncInterval  String   @default("daily")
   createdAt        DateTime @default(now())
   updatedAt        DateTime @updatedAt
+  user             User     @relation(fields: [userId], references: [id], onDelete: Cascade)
 
   @@map("user_preferences")
 }