refactor: unify date handling with utility functions

- Replaced direct date manipulations with utility functions like `getToday`, `parseDate`, and `createDateFromParts` across various components and services for consistency.
- Updated date initialization in `JiraAnalyticsService`, `BackupService`, and `DailyClient` to improve clarity and maintainability.
- Enhanced date parsing in forms and API routes to ensure proper handling of date strings.

src/app/daily/page.tsx

@@ -1,6 +1,7 @@
 import { Metadata } from 'next';
 import { DailyPageClient } from './DailyPageClient';
 import { dailyService } from '@/services/daily';
+import { getToday } from '@/lib/date-utils';
 
 // Force dynamic rendering (no static generation)
 export const dynamic = 'force-dynamic';
@@ -12,7 +13,7 @@ export const metadata: Metadata = {
 
 export default async function DailyPage() {
   // Récupérer les données côté serveur
-  const today = new Date();
+  const today = getToday();
   
   try {
     const [dailyView, dailyDates] = await Promise.all([