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

docs/CURRENT-STATE.md

@@ -3445,7 +3445,24 @@ Providers normalize coordinates, canonical name, label, place types and optional
 bounds. Camera framing, nearby landmark recovery and footprint selection remain
 in their consumers, including the Capitol identity/containment safeguards.
 Radio keeps localized country names in labels rather than station filters.
-Reverse geocoding and nearby/text-search endpoints retain their existing behavior.
+Nearby/text-search endpoints retain their existing behavior.
+
+**Google geocoding is a server route, not a browser call** (#363). Forward and
+reverse lookups go to `/api/google/geocode` and `/api/google/reverse-geocode`,
+which carry `GOOGLE_MAPS_SERVER_API_KEY` (falling back to `GOOGLE_MAPS_API_KEY`)
+and share the Places routes' opt-in `GEV_RATELIMIT_GOOGLE_PER_MIN` throttle.
+Google's Geocoding **web service** refuses referrer-restricted keys, so the
+previous browser call forced the bundled browser key — visible in devtools by
+design — to be left unrestricted; it now needs the Map Tiles API only. Both
+routes answer in Google's own `status`/`results` shape rather than the Places
+routes' `places: []` contract, because the browser adapters normalize that shape
+directly. The browser key still gates the provider client-side, so a keyless
+session spends no request to learn it has no Google: the route's own keyless
+answer reads as an unanswered provider, which would stop the chain caching the
+negative Photon or Nominatim then produces. Its query is capped at 200
+characters, its reverse coordinates are validated against WGS84 bounds before
+the request is paid for, and a malformed viewport bias is dropped rather than
+refused, since a bias only ranks results.
 
 Only valid answers and definitive misses enter bounded caches; malformed replies,
 HTTP refusals and outages remain retryable. Searches share a 12-second total