fix(planner): distinct aria-label for export dropdown toggle

The restyled Export split-button's dropdown toggle got aria-label
"Export GPX", colliding with the main button's text and breaking the
E2E selector that clicked the old "▾" glyph. Give it a dedicated
exportOptions label (en + de) and target it in the E2E test.

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

packages/i18n/src/locales/de.ts

@@ -18,6 +18,7 @@ export default {
     newSession: "Neue Sitzung",
     saveRoute: "Route speichern",
     exportGpx: "GPX exportieren",
+    exportOptions: "Export-Optionen",
     exportRoute: "Route exportieren",
     exportRouteDesc: "GPX-Track für jede App",
     exportPlan: "Plan exportieren",

packages/i18n/src/locales/en.ts

@@ -18,6 +18,7 @@ export default {
     newSession: "New Session",
     saveRoute: "Save Route",
     exportGpx: "Export GPX",
+    exportOptions: "Export options",
     exportRoute: "Export Route",
     exportRouteDesc: "Clean GPX track for any app",
     exportPlan: "Export Plan",