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/es.json

@@ -0,0 +1,50 @@
+{
+  "app.title": "OmniMTP",
+  "badge.no_device": "Sin dispositivo",
+  "device.waiting": "Esperando Nintendo Switch…",
+  "device.connected": "{name} conectada",
+  "device.nintendo_switch": "Nintendo Switch",
+  "btn.add_files": "Añadir archivos",
+  "btn.scan": "Buscar",
+  "btn.cancel_all": "Cancelar todo",
+  "btn.go_up": "Subir",
+  "btn.refresh": "Actualizar",
+  "empty.no_switch_title": "Ninguna Switch conectada",
+  "empty.no_switch_sub": "Conecta por USB-C y abre DBI o Sphaira MTP",
+  "empty.folder": "Carpeta vacía",
+  "loading": "Cargando…",
+  "col.name": "Nombre",
+  "col.size": "Tamaño",
+  "col.modified": "Modificado",
+  "transfers": "Transferencias",
+  "transfers.count": "{n} transferencia",
+  "transfers.count_plural": "{n} transferencias",
+  "transfer.queued": "En cola",
+  "transfer.done": "Hecho",
+  "transfer.failed": "Error",
+  "transfer.cancelled": "Cancelado",
+  "transfer.dl": "DL",
+  "transfer.up": "UP",
+  "ctx.delete": "Eliminar…",
+  "confirm.delete": "¿Eliminar {label}?",
+  "confirm.delete_items": "¿Eliminar {n} elementos?",
+  "confirm.delete_btn": "Eliminar",
+  "confirm.cancel_btn": "Cancelar",
+  "confirm.ok_btn": "OK",
+  "items.count": "{n} elemento",
+  "items.count_plural": "{n} elementos",
+  "status.active": "{n} activo · {speed}",
+  "status.connected": "Conectado  {name}",
+  "status.disconnected": "Switch desconectada",
+  "status.listing_error": "Error al listar: {error}",
+  "status.downloading": "Descargando  {name}",
+  "status.uploading": "Subiendo  {name}",
+  "menu.options": "Opciones",
+  "menu.language": "Idioma",
+  "menu.language_system": "Idioma del sistema",
+  "menu.quit": "Salir de OmniMTP",
+  "menu.about": "Acerca de OmniMTP",
+  "about.tagline": "Cliente MTP de Nintendo Switch para macOS",
+  "about.version": "Versión {version}",
+  "about.copyright": "Copyright © 2026 NiklasCFW"
+}