fix(search): geocode through the server, not the browser

- Google's Geocoding web service refuses referrer-restricted keys, so the
  browser call forced GOOGLE_MAPS_API_KEY to ship unrestricted
- add /api/google/geocode and /api/google/reverse-geocode, using the server
  key like Places and Street View already do
- the browser key now needs the Map Tiles API only

src/annotations/annotationEngine.test.mjs

@@ -400,7 +400,7 @@ test('outline upgrade updates the rendered element in place without remove/add',
   };
   let overpassCall = 0;
   globalThis.fetch = async (url) => {
-    if (String(url).startsWith('https://maps.googleapis.com/')) {
+    if (String(url).startsWith('/api/google/geocode')) {
       return { json: async () => ({
         status: 'OK',
         results: [{