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/nl.json

@@ -0,0 +1,50 @@
+{
+  "app.title": "OmniMTP",
+  "badge.no_device": "Geen apparaat",
+  "device.waiting": "Wachten op Nintendo Switch…",
+  "device.connected": "{name} verbonden",
+  "device.nintendo_switch": "Nintendo Switch",
+  "btn.add_files": "Bestanden toevoegen",
+  "btn.scan": "Zoeken",
+  "btn.cancel_all": "Alles annuleren",
+  "btn.go_up": "Omhoog",
+  "btn.refresh": "Vernieuwen",
+  "empty.no_switch_title": "Geen Switch verbonden",
+  "empty.no_switch_sub": "Verbind via USB-C en open DBI of Sphaira MTP",
+  "empty.folder": "Lege map",
+  "loading": "Laden…",
+  "col.name": "Naam",
+  "col.size": "Grootte",
+  "col.modified": "Gewijzigd",
+  "transfers": "Overdrachten",
+  "transfers.count": "{n} overdracht",
+  "transfers.count_plural": "{n} overdrachten",
+  "transfer.queued": "Wachtrij",
+  "transfer.done": "Klaar",
+  "transfer.failed": "Mislukt",
+  "transfer.cancelled": "Geannuleerd",
+  "transfer.dl": "DL",
+  "transfer.up": "UP",
+  "ctx.delete": "Verwijderen…",
+  "confirm.delete": "{label} verwijderen?",
+  "confirm.delete_items": "{n} items verwijderen?",
+  "confirm.delete_btn": "Verwijderen",
+  "confirm.cancel_btn": "Annuleren",
+  "confirm.ok_btn": "OK",
+  "items.count": "{n} item",
+  "items.count_plural": "{n} items",
+  "status.active": "{n} actief · {speed}",
+  "status.connected": "Verbonden  {name}",
+  "status.disconnected": "Switch verbroken",
+  "status.listing_error": "Fout bij weergeven: {error}",
+  "status.downloading": "Downloaden  {name}",
+  "status.uploading": "Uploaden  {name}",
+  "menu.options": "Opties",
+  "menu.language": "Taal",
+  "menu.language_system": "Systeemstandaard",
+  "menu.quit": "OmniMTP afsluiten",
+  "menu.about": "Over OmniMTP",
+  "about.tagline": "Nintendo Switch MTP-client voor macOS",
+  "about.version": "Versie {version}",
+  "about.copyright": "Copyright © 2026 NiklasCFW"
+}