feat: GPX file import for places — closes #98

Upload a GPX file to automatically create places from waypoints.
Supports <wpt>, <rtept>, and <trkpt> elements with CDATA handling.
Handles lat/lon in any attribute order. Track-only files import
start and end points with the track name.

- New server endpoint POST /places/import/gpx
- Import GPX button in PlacesSidebar below Add Place
- i18n keys for DE and EN

client/src/i18n/translations/de.ts

@@ -638,6 +638,9 @@ const de: Record<string, string | { name: string; category: string }[]> = {
 
   // Places Sidebar
   'places.addPlace': 'Ort/Aktivität hinzufügen',
+  'places.importGpx': 'GPX importieren',
+  'places.gpxImported': '{count} Orte aus GPX importiert',
+  'places.gpxError': 'GPX-Import fehlgeschlagen',
   'places.assignToDay': 'Zu welchem Tag hinzufügen?',
   'places.all': 'Alle',
   'places.unplanned': 'Ungeplant',

client/src/i18n/translations/en.ts

@@ -638,6 +638,9 @@ const en: Record<string, string | { name: string; category: string }[]> = {
 
   // Places Sidebar
   'places.addPlace': 'Add Place/Activity',
+  'places.importGpx': 'Import GPX',
+  'places.gpxImported': '{count} places imported from GPX',
+  'places.gpxError': 'GPX import failed',
   'places.assignToDay': 'Add to which day?',
   'places.all': 'All',
   'places.unplanned': 'Unplanned',