Replace Google Places autocomplete with OSM/gsc-geocoder

useAddressAutocomplete: drop the Google Maps JS SDK + loadGoogleMapsScript
in favor of an HTTP-fetch loop against a configurable endpoint (default
/api/geocoder), which we point at gsc-geocoder (183M-row OSM-derived
PostGIS database). Promote AddressAutocomplete from gscRegister fork into
the shared validation/components/. Pre-existing Google Maps TS namespace
issues vanish with the dep removal.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

package.json

@@ -53,7 +53,6 @@
     "react-dom": "^18.2.0 || ^19.0.0"
   },
   "devDependencies": {
-    "@types/google.maps": "^3.55.0",
     "@types/nodemailer": "^6.4.0",
     "@types/react": "^19.0.0",
     "@types/react-dom": "^19.0.0",