Einzelbeleg: CI poi pin from the receipt address, plus a centre button

The station marker was a red circleMarker. It is now the CI poi pin
(poi-l/poi-s via tankstellenMarkerSVG) - the plain pin rather than poi-car, so
the vehicle and the station stay distinguishable on a map.

While testing it turned out nothing in the backend ever writes station_lat /
station_lon, so that marker had never been reachable in practice. The receipt
address is now geocoded in the frontend via Nominatim /search
(adresseAufloesen, the forward counterpart to the existing reverse lookup),
with results cached in localStorage - negative ones too, since a station
address does not move and Nominatim's terms ask for caching. Verified live:
"Shell, SÖLDEN" resolves to 46.9756 / 11.0111.

The map card gained a centre button (CI.gps, which is byte-identical to the
delivered gps-s.svg), disabled until the coordinates arrive. .mapbox needed
position:relative so the control anchors to the card instead of an ancestor.
Only in the Einzelbeleg, as requested - the Standort fullscreen already has
its own centre controls.

Co-Authored-By: Claude Opus 5 <[email protected]>

homeassistant/www/audi-dashboard-version.json

@@ -1 +1 @@
-{"version": 1786766000}
+{"version": 1786769000}