feat(online): partage sortant et boîte de réception (ticket #69)

Ajoute l'écran de partage sortant (presentation/share_screen.dart) et
la boîte de réception des partages (presentation/share_inbox_screen.dart),
avec les points d'entrée sur profile_screen.dart, home_screen.dart,
program_screen.dart et workout_template_screen.dart. flutter analyze
propre (mêmes infos préexistantes), 132/132 tests verts, build APK
debug validé. Dernier ticket de développement du chantier "Ajouter
les features serveur au client" (#63) — il ne reste que la QA finale
(#70).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/presentation/profile_screen.dart

@@ -2,17 +2,20 @@ import 'package:flutter/material.dart';
 
 import '../application/application.dart';
 import '../domain/domain.dart';
+import 'share_inbox_screen.dart';
 import 'theme.dart';
 
 final class ProfileScreen extends StatefulWidget {
   const ProfileScreen({
     required this.authUseCases,
     required this.syncUseCases,
+    required this.shareUseCases,
     super.key,
   });
 
   final AuthUseCases authUseCases;
   final SyncUseCases syncUseCases;
+  final ShareUseCases shareUseCases;
 
   @override
   State<ProfileScreen> createState() => _ProfileScreenState();
@@ -122,7 +125,10 @@ final class _ProfileScreenState extends State<ProfileScreen> {
 
   void _openReceivedShares(BuildContext context) {
     Navigator.of(context).push(
-      MaterialPageRoute(builder: (context) => const ReceivedSharesScreen()),
+      MaterialPageRoute(
+        builder: (context) =>
+            ShareInboxScreen(shareUseCases: widget.shareUseCases),
+      ),
     );
   }
 
@@ -672,26 +678,6 @@ final class _RegisterScreenState extends State<RegisterScreen> {
   }
 }
 
-final class ReceivedSharesScreen extends StatelessWidget {
-  const ReceivedSharesScreen({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(title: const Text('Partages reçus')),
-      body: const Center(
-        child: Padding(
-          padding: EdgeInsets.all(24),
-          child: Text(
-            "Les programmes et séances qu'on t'envoie apparaîtront ici.",
-            textAlign: TextAlign.center,
-          ),
-        ),
-      ),
-    );
-  }
-}
-
 final class _AuthFormScaffold extends StatelessWidget {
   const _AuthFormScaffold({required this.child});