fix(expo): harden account deletion handler

- Add isDeletingAccount ref to prevent double-tap race
- Guard against null session before calling API
- Set 15s timeout on delete request (API makes 3-4 Supabase round-trips)
- Log error to console and restore guard in finally block

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

xtablo-expo/app/(app)/(tabs)/settings.tsx

@@ -61,6 +61,7 @@ export default function SettingsScreen() {
   const [pushNotifications, setPushNotifications] = useState(true);
   const [emailNotifications, setEmailNotifications] = useState(true);
   const [biometricAuth, setBiometricAuth] = useState(false);
+  const isDeletingAccount = React.useRef(false);
 
   const handleSignOut = () => {
     Alert.alert("Déconnexion", "Êtes-vous sûr de vouloir vous déconnecter ?", [
@@ -90,17 +91,27 @@ export default function SettingsScreen() {
           text: "Supprimer mon compte",
           style: "destructive",
           onPress: async () => {
+            if (isDeletingAccount.current) return;
+            isDeletingAccount.current = true;
             try {
               const session = useAuthStore.getState().session;
+              if (!session) {
+                Alert.alert("Erreur", "Session expirée. Veuillez vous reconnecter.");
+                return;
+              }
               await api.delete("/api/v1/users/me", {
-                headers: { Authorization: `Bearer ${session?.access_token}` },
+                headers: { Authorization: `Bearer ${session.access_token}` },
+                timeout: 15000,
               });
               await signOut();
-            } catch {
+            } catch (error) {
+              console.error("Account deletion error:", error);
               Alert.alert(
                 "Erreur",
                 "Une erreur est survenue lors de la suppression de votre compte. Veuillez réessayer."
               );
+            } finally {
+              isDeletingAccount.current = false;
             }
           },
         },