refactor: Rename date parsing helper functions for consistency

em2rp/lib/services/ics_export_service.dart

@@ -16,7 +16,7 @@ class IcsExportService {
     Map<String, String>? optionNames,
   }) async {
     final now = DateTime.now().toUtc();
-    final timestamp = DateFormat('yyyyMMddTHHmmss').format(now) + 'Z';
+    final timestamp = '${DateFormat('yyyyMMddTHHmmss').format(now)}Z';
 
     // Récupérer les informations supplémentaires
     final resolvedEventTypeName = eventTypeName ?? await _getEventTypeName(event.eventTypeId);
@@ -238,7 +238,7 @@ END:VCALENDAR''';
   /// Formate une date au format ICS (yyyyMMddTHHmmssZ)
   static String _formatDateForIcs(DateTime dateTime) {
     final utcDate = dateTime.toUtc();
-    return DateFormat('yyyyMMddTHHmmss').format(utcDate) + 'Z';
+    return '${DateFormat('yyyyMMddTHHmmss').format(utcDate)}Z';
   }
 
   /// Échappe les caractères spéciaux pour le format ICS

em2rp/lib/services/pdf_service.dart

@@ -1,4 +1,3 @@
-import 'dart:typed_data';
 import 'package:flutter/services.dart';
 import 'package:pdf/pdf.dart';
 import 'package:pdf/widgets.dart' as pw;

em2rp/lib/services/qr_code_service.dart

@@ -1,4 +1,3 @@
-import 'dart:typed_data';
 import 'dart:ui' as ui;
 import 'package:flutter/services.dart';
 import 'package:qr_flutter/qr_flutter.dart';