feat: refactor daily task management with new pending tasks section

- Added `PendingTasksSection` to `DailyPageClient` for displaying uncompleted tasks.
- Implemented `getPendingCheckboxes` method in `DailyClient` and `DailyService` to fetch pending tasks.
- Introduced `getDaysAgo` utility function for calculating elapsed days since a date.
- Updated `TODO.md` to reflect the new task management features and adjustments.
- Cleaned up and organized folder structure to align with Next.js 13+ best practices.

src/lib/date-utils.ts

@@ -63,6 +63,15 @@ export function formatDateShort(date: Date): string {
   return formatDateForDisplay(date, 'DISPLAY_SHORT');
 }
 
+/**
+ * Calcule le nombre de jours écoulés depuis une date
+ */
+export function getDaysAgo(date: Date): number {
+  const today = getToday();
+  const diffTime = today.getTime() - normalizeDate(date).getTime();
+  return Math.floor(diffTime / (1000 * 60 * 60 * 24));
+}
+
 /**
  * Formate une date longue pour l'affichage (lundi 1 décembre 2025)
  */