Improve Switch-only MTP UI with drag export, i18n, and polish.

Ship Finder-style drag-out for files and folders, system-language packs with an Options override, About/menu bar support, and sorting plus selection UX fixes.

src/ui/webroot/lang/fr.json

@@ -0,0 +1,50 @@
+{
+  "app.title": "OmniMTP",
+  "badge.no_device": "Aucun appareil",
+  "device.waiting": "En attente de la Nintendo Switch…",
+  "device.connected": "{name} connectée",
+  "device.nintendo_switch": "Nintendo Switch",
+  "btn.add_files": "Ajouter des fichiers",
+  "btn.scan": "Rechercher",
+  "btn.cancel_all": "Tout annuler",
+  "btn.go_up": "Remonter",
+  "btn.refresh": "Actualiser",
+  "empty.no_switch_title": "Aucune Switch connectée",
+  "empty.no_switch_sub": "Connectez en USB-C et ouvrez DBI ou Sphaira MTP",
+  "empty.folder": "Dossier vide",
+  "loading": "Chargement…",
+  "col.name": "Nom",
+  "col.size": "Taille",
+  "col.modified": "Modifié",
+  "transfers": "Transferts",
+  "transfers.count": "{n} transfert",
+  "transfers.count_plural": "{n} transferts",
+  "transfer.queued": "En file",
+  "transfer.done": "Terminé",
+  "transfer.failed": "Échoué",
+  "transfer.cancelled": "Annulé",
+  "transfer.dl": "DL",
+  "transfer.up": "UP",
+  "ctx.delete": "Supprimer…",
+  "confirm.delete": "Supprimer {label} ?",
+  "confirm.delete_items": "Supprimer {n} éléments ?",
+  "confirm.delete_btn": "Supprimer",
+  "confirm.cancel_btn": "Annuler",
+  "confirm.ok_btn": "OK",
+  "items.count": "{n} élément",
+  "items.count_plural": "{n} éléments",
+  "status.active": "{n} actif · {speed}",
+  "status.connected": "Connecté  {name}",
+  "status.disconnected": "Switch déconnectée",
+  "status.listing_error": "Erreur de listage : {error}",
+  "status.downloading": "Téléchargement  {name}",
+  "status.uploading": "Envoi  {name}",
+  "menu.options": "Options",
+  "menu.language": "Langue",
+  "menu.language_system": "Langue du système",
+  "menu.quit": "Quitter OmniMTP",
+  "menu.about": "À propos d’OmniMTP",
+  "about.tagline": "Client MTP Nintendo Switch pour macOS",
+  "about.version": "Version {version}",
+  "about.copyright": "Copyright © 2026 NiklasCFW"
+}