Add descriptions to export dropdown, fix z-index and alignment

- Add description text below each export option explaining the difference
- Fix z-index (z-[1001]) so dropdown renders above the map
- Align dropdown left instead of right to avoid overflow
- Widen dropdown (w-56) to fit descriptions

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

packages/i18n/src/locales/de.ts

@@ -19,7 +19,9 @@ export default {
     saveRoute: "Route speichern",
     exportGpx: "GPX exportieren",
     exportRoute: "Route exportieren",
+    exportRouteDesc: "GPX-Track für jede App",
     exportPlan: "Plan exportieren",
+    exportPlanDesc: "Mit Wegpunkten und Sperrzonen",
     profile: "Profil",
     connecting: "Verbinde...",
     loadingMap: "Karte wird geladen...",

packages/i18n/src/locales/en.ts

@@ -19,7 +19,9 @@ export default {
     saveRoute: "Save Route",
     exportGpx: "Export GPX",
     exportRoute: "Export Route",
+    exportRouteDesc: "Clean GPX track for any app",
     exportPlan: "Export Plan",
+    exportPlanDesc: "Includes waypoints and no-go areas",
     profile: "Profile",
     connecting: "Connecting...",
     loadingMap: "Loading map...",