skip Nominatim lookups when the server has none configured

Add GET /api/geocode/status ({configured}), like /api/overpass/status. The outline client and the last-resort place search ask it once per page and send no lookup a server without a Nominatim endpoint would refuse, so a default install no longer logs a 503 on its first named landmark or grounds ask. An older server or a failed probe leaves the capability unknown and lookups proceed as before.

scripts/package-boundaries.json

@@ -396,6 +396,7 @@
       "src/search/geospatial.js",
       "src/search/http.js",
       "src/search/defaults.js",
+      "src/sources/nominatimStatus.js",
       "src/search/alpsGeocoder.js",
       "src/search/coordinateGeocoder.js",
       "src/search/coordinateParser.js",
@@ -2822,6 +2823,7 @@
       "src/annotations/outlineRungs.js",
       "src/sources/openFreeMapOutlines.js",
       "src/sources/nominatimOutlines.js",
+      "src/sources/nominatimStatus.js",
       "src/data/placeBoundaries.js",
       "src/data/placeNames.js",
       "src/data/local_data/us_census_places/files.js",
@@ -3413,6 +3415,7 @@
       "src/annotations/outlineRungs.js",
       "src/sources/openFreeMapOutlines.js",
       "src/sources/nominatimOutlines.js",
+      "src/sources/nominatimStatus.js",
       "src/data/placeBoundaries.js",
       "src/data/placeNames.js",
       "src/data/local_data/us_census_places/files.js",
@@ -3496,6 +3499,7 @@
       "src/annotations/outlineRungs.js",
       "src/sources/openFreeMapOutlines.js",
       "src/sources/nominatimOutlines.js",
+      "src/sources/nominatimStatus.js",
       "src/data/placeBoundaries.js",
       "src/data/placeNames.js",
       "src/data/local_data/us_census_places/files.js",