feat: page de telechargement des applications mobiles (Android / iOS)

Page publique /telecharger reprenant le modele de Ressources-relationnel :
- config/mobile.php (lien de store prioritaire, sinon binaire local, sinon 'bientot')
- DownloadController + vue au style DSFR, lien dans la sidebar
- variables MOBILE_* et depot public/downloads/ (binaires gitignores)
- 3 tests (page publique, lien store, bouton desactive)

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

WEB/routes/web.php

@@ -3,6 +3,7 @@
 use App\Http\Controllers\DashboardController;
 use App\Http\Controllers\Web\AuthController;
 use App\Http\Controllers\Web\DiagnosticController;
+use App\Http\Controllers\Web\DownloadController;
 use App\Http\Controllers\Web\EmotionController;
 use App\Http\Controllers\Web\InformationController;
 use App\Http\Controllers\Web\ProfileController;
@@ -17,6 +18,9 @@ Route::get('/relaxation', [RelaxationController::class, 'index'])->name('relaxat
 Route::get('/informations', [InformationController::class, 'index'])->name('informations.index');
 Route::get('/informations/{id}', [InformationController::class, 'show'])->name('informations.show');
 
+// Téléchargement des applications mobiles (Android / iOS)
+Route::get('/telecharger', [DownloadController::class, 'index'])->name('telecharger');
+
 // Authentification
 Route::get('/login', [AuthController::class, 'showLogin'])->name('login');
 Route::post('/login', [AuthController::class, 'login']);