feat: Redesign calendar page with default week view, improved app bar, and a consolidated activity timeline.

lib/components/activities/add_activity_bottom_sheet.dart

@@ -26,6 +26,7 @@ class _AddActivityBottomSheetState extends State<AddActivityBottomSheet> {
   final ErrorService _errorService = ErrorService();
 
   ActivityCategory _selectedCategory = ActivityCategory.attraction;
+  DateTime? _selectedDate;
   bool _isLoading = false;
 
   @override
@@ -150,6 +151,13 @@ class _AddActivityBottomSheetState extends State<AddActivityBottomSheet> {
                       icon: Icons.location_on,
                     ),
 
+                    const SizedBox(height: 20),
+
+                    // Date et heure (optionnel)
+                    _buildSectionTitle('Date et heure (optionnel)'),
+                    const SizedBox(height: 8),
+                    _buildDateTimePicker(),
+
                     const SizedBox(height: 40),
 
                     // Boutons d'action
@@ -369,6 +377,7 @@ class _AddActivityBottomSheetState extends State<AddActivityBottomSheet> {
         votes: {},
         createdAt: DateTime.now(),
         updatedAt: DateTime.now(),
+        date: _selectedDate,
         createdBy: FirebaseAuth.instance.currentUser?.uid,
       );
 
@@ -414,4 +423,92 @@ class _AddActivityBottomSheetState extends State<AddActivityBottomSheet> {
         return Icons.spa;
     }
   }
+
+  Widget _buildDateTimePicker() {
+    final theme = Theme.of(context);
+    final isDarkMode = theme.brightness == Brightness.dark;
+
+    return InkWell(
+      onTap: _pickDateTime,
+      borderRadius: BorderRadius.circular(12),
+      child: Container(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 16),
+        decoration: BoxDecoration(
+          color: theme.colorScheme.surface,
+          borderRadius: BorderRadius.circular(12),
+          border: Border.all(
+            color: isDarkMode
+                ? Colors.white.withValues(alpha: 0.2)
+                : Colors.black.withValues(alpha: 0.2),
+          ),
+        ),
+        child: Row(
+          children: [
+            Icon(
+              Icons.calendar_today,
+              color: theme.colorScheme.onSurface.withValues(alpha: 0.6),
+            ),
+            const SizedBox(width: 12),
+            Text(
+              _selectedDate != null
+                  ? '${_selectedDate!.day}/${_selectedDate!.month}/${_selectedDate!.year} à ${_selectedDate!.hour}:${_selectedDate!.minute.toString().padLeft(2, '0')}'
+                  : 'Choisir une date et une heure',
+              style: theme.textTheme.bodyMedium?.copyWith(
+                color: _selectedDate != null
+                    ? theme.colorScheme.onSurface
+                    : theme.colorScheme.onSurface.withValues(alpha: 0.6),
+              ),
+            ),
+            const Spacer(),
+            if (_selectedDate != null)
+              IconButton(
+                icon: const Icon(Icons.clear, size: 20),
+                onPressed: () {
+                  setState(() {
+                    _selectedDate = null;
+                  });
+                },
+                padding: EdgeInsets.zero,
+                constraints: const BoxConstraints(),
+              ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Future<void> _pickDateTime() async {
+    final now = DateTime.now();
+    final initialDate = widget.trip.startDate.isAfter(now)
+        ? widget.trip.startDate
+        : now;
+
+    final date = await showDatePicker(
+      context: context,
+      initialDate: _selectedDate ?? initialDate,
+      firstDate: now.subtract(const Duration(days: 365)),
+      lastDate: now.add(const Duration(days: 365 * 2)),
+    );
+
+    if (date == null) return;
+
+    if (!mounted) return;
+
+    final time = await showTimePicker(
+      context: context,
+      initialTime: TimeOfDay.fromDateTime(_selectedDate ?? now),
+    );
+
+    if (time == null) return;
+
+    setState(() {
+      _selectedDate = DateTime(
+        date.year,
+        date.month,
+        date.day,
+        time.hour,
+        time.minute,
+      );
+    });
+  }
 }