feat(geoportal): add search, basemap switcher, feature info panel, selection + export

Major geoportal enhancements:
- Basemap switcher (OSM/Satellite/Terrain) with ESRI + OpenTopoMap tiles
- Search bar with debounced lookup (UATs by name, parcels by cadastral ref, owners by name)
- Feature info panel showing enrichment data from ParcelSync (cadastru, proprietari, suprafata, folosinta)
- Parcel selection mode with amber highlight + export (GeoJSON/DXF/GPKG via ogr2ogr)
- Next.js /tiles rewrite proxying to Martin (fixes dev + avoids mixed content)
- Fixed MapLibre web worker relative URL resolution (window.location.origin)

API routes: /api/geoportal/search, /api/geoportal/feature, /api/geoportal/export

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

next.config.ts

@@ -6,6 +6,15 @@ const nextConfig: NextConfig = {
   experimental: {
     middlewareClientMaxBodySize: '500mb',
   },
+  async rewrites() {
+    const martinUrl = process.env.MARTIN_URL || 'http://martin:3000';
+    return [
+      {
+        source: '/tiles/:path*',
+        destination: `${martinUrl}/:path*`,
+      },
+    ];
+  },
 };
 
 export default nextConfig;