[#101] [Frontend] Inscription parent — API, soumission et validation

Squash merge de develop vers master.

Livrables principaux (ticket #101 et mise au point associée) :
- Branchement du formulaire d'inscription parent sur POST /api/v1/auth/register/parent
- Payload DTO (parents, enfants, photos base64, CGU) et services Auth
- Parcours gestionnaire : cartes dossiers, wizard validation famille, images authentifiées
- Scripts d'inscription test (Martin, Durand/Rousseau, Lecomte) ; .gitignore .cursor/

Inclut également les ajustements develop fusionnés dans ce lot (inscription AM, champs relais, etc.).

Closes #101

Made-with: Cursor

frontend/lib/screens/auth/parent_register_step5_screen.dart

@@ -13,6 +13,7 @@ import '../../widgets/custom_navigation_button.dart';
 import '../../widgets/personal_info_form_screen.dart';
 import '../../widgets/child_card_widget.dart';
 import '../../widgets/presentation_form_screen.dart';
+import '../../services/auth_service.dart';
 
 class ParentRegisterStep5Screen extends StatefulWidget {
   const ParentRegisterStep5Screen({super.key});
@@ -22,6 +23,36 @@ class ParentRegisterStep5Screen extends StatefulWidget {
 }
 
 class _ParentRegisterStep5ScreenState extends State<ParentRegisterStep5Screen> {
+  bool _isSubmitting = false;
+
+  Future<void> _submitRegistration(BuildContext context, UserRegistrationData data) async {
+    if (_isSubmitting) return;
+    setState(() => _isSubmitting = true);
+    try {
+      await AuthService.registerParent(data);
+      if (!context.mounted) return;
+      _showSuccessModal(context);
+    } catch (e) {
+      if (!context.mounted) return;
+      final msg = e.toString().replaceAll('Exception: ', '');
+      await showDialog<void>(
+        context: context,
+        builder: (ctx) => AlertDialog(
+          title: Text('Envoi impossible', style: GoogleFonts.merienda(fontWeight: FontWeight.bold)),
+          content: Text(msg, style: GoogleFonts.merienda(fontSize: 14)),
+          actions: [
+            TextButton(
+              onPressed: () => Navigator.of(ctx).pop(),
+              child: Text('OK', style: GoogleFonts.merienda(fontWeight: FontWeight.bold)),
+            ),
+          ],
+        ),
+      );
+    } finally {
+      if (mounted) setState(() => _isSubmitting = false);
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final registrationData = Provider.of<UserRegistrationData>(context);
@@ -102,12 +133,11 @@ class _ParentRegisterStep5ScreenState extends State<ParentRegisterStep5Screen> {
                             Expanded(
                               child: HoverReliefWidget(
                                 child: CustomNavigationButton(
-                                  text: 'Soumettre',
+                                  text: _isSubmitting ? 'Envoi…' : 'Soumettre',
                                   style: NavigationButtonStyle.green,
-                                  onPressed: () {
-                                    print("Données finales: ${registrationData.parent1.firstName}, Enfant(s): ${registrationData.children.length}");
-                                    _showConfirmationModal(context);
-                                  },
+                                  onPressed: _isSubmitting
+                                      ? () {}
+                                      : () => _submitRegistration(context, registrationData),
                                   width: double.infinity,
                                   height: 50,
                                   fontSize: 16,
@@ -118,18 +148,20 @@ class _ParentRegisterStep5ScreenState extends State<ParentRegisterStep5Screen> {
                         ),
                       )
                     else
-                      ImageButton(
-                        bg: 'assets/images/bg_green.png',
-                        text: 'Soumettre ma demande',
-                        textColor: const Color(0xFF2D6A4F),
-                        width: 350,
-                        height: 50,
-                        fontSize: 18,
-                        onPressed: () {
-                          print("Données finales: ${registrationData.parent1.firstName}, Enfant(s): ${registrationData.children.length}");
-                          _showConfirmationModal(context);
-                        },
-                      ),
+                      _isSubmitting
+                          ? const Padding(
+                              padding: EdgeInsets.all(16),
+                              child: CircularProgressIndicator(),
+                            )
+                          : ImageButton(
+                              bg: 'assets/images/bg_green.png',
+                              text: 'Soumettre ma demande',
+                              textColor: const Color(0xFF2D6A4F),
+                              width: 350,
+                              height: 50,
+                              fontSize: 18,
+                              onPressed: () => _submitRegistration(context, registrationData),
+                            ),
                   ],
                 ),
               ),
@@ -216,11 +248,12 @@ class _ParentRegisterStep5ScreenState extends State<ParentRegisterStep5Screen> {
           childIndex: index,
           mode: DisplayMode.readonly,
           onPickImage: () {},
+          onClearImage: () {},
           onDateSelect: () {},
           onFirstNameChanged: (v) {},
           onLastNameChanged: (v) {},
+          onGenreChanged: (v) {},
           onTogglePhotoConsent: (v) {},
-          onToggleMultipleBirth: (v) {},
           onToggleIsUnborn: (v) {},
           onRemove: () {},
           canBeRemoved: false,
@@ -239,14 +272,14 @@ class _ParentRegisterStep5ScreenState extends State<ParentRegisterStep5Screen> {
       cardColor: CardColorHorizontal.green, // Changé de pink à green
       textFieldHint: '',
       initialText: data.motivationText,
-      initialCguAccepted: true, // Toujours true ici car déjà passé
+      initialCguAccepted: data.cguAccepted,
       previousRoute: '',
       onSubmit: (t, c) {},
       onEdit: () => context.go('/parent-register-step4'),
     );
   }
 
-  void _showConfirmationModal(BuildContext context) {
+  void _showSuccessModal(BuildContext context) {
     showDialog<void>(
       context: context,
       barrierDismissible: false,