Correct date handling for task due dates to prevent errors

Update the schema to use the `date` type for due dates instead of `timestamp` to resolve a TypeError when creating tasks.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: cc2d271b-82f0-4d6a-9302-a0b067ffb429
Replit-Commit-Checkpoint-Type: full_checkpoint
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shared/schema.ts

@@ -248,7 +248,7 @@ export const tasks = pgTable("tasks", {
   id: serial("id").primaryKey(),
   title: varchar("title").notNull(), // Titre de la tâche (requis)
   description: text("description"), // Description de la tâche (optionnel)
-  dueDate: timestamp("due_date"), // Date d'échéance (optionnel)
+  dueDate: date("due_date"), // Date d'échéance (optionnel)
   priority: varchar("priority").notNull().default("medium"), // low, medium, high
   status: varchar("status").notNull().default("pending"), // pending, completed
   assignedTo: text("assigned_to").notNull(), // Utilisateur responsable (champ libre)