Fix broken map rendering, split GPS cleanup, receipt parser and design backlog

Leaflet's stylesheet was appended to document.head, so it never reached the
panel's shadow root: .leaflet-tile{position:absolute} never applied, tiles laid
out as in-flow images (~1040px inside a 190px box) and the marker pane ended up
far below the visible area. That is the real cause of the long-standing
"fragmented Leaflet rendering" finding and of the invisible vehicle pin - every
tile request had actually succeeded. The stylesheet now goes into the shadow
root and is awaited before the map is built.

Also in this round:
- Map tiles are always light (Google-Maps-style), no dark variant at night.
- Vehicle marker uses the real CI poi-car icons (poi-car-l >=34px, poi-car-s
  below), with a white halo so the outline stays readable on tiles.
- Removed the obsolete combined STANDORT_TRACKER field; only the split
  lat/lon sensors remain.
- Receipt upload: widened the try block so base64/save failures surface, and
  the frontend call site now reports a rejected service call.
- Generic receipt parser: total detection is line-based (letter-spaced
  headings, no more matching the SUMME-EUR column header, tax lines excluded),
  address heuristic handles 4-digit postcodes and single-line address blocks,
  and "Preis/L" matches without a spelled-out "Liter".
- Design backlog: red hairline frame on list rows (delete button bled through
  at fractional row heights) and select fields now use the grey background box.

Shell 10-receipt regression suite still passes; all changes verified live in
the audi_ha_test container.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

homeassistant/INSTALL.md

@@ -177,8 +177,11 @@ Oberfläche „unbekannt"/em-dash statt eines Werts, kein Absturz:
   (`RANGE_SENSOR`) — bis zu einer neuen Datenquelle unbelegt, siehe
   `AGENTS.md` (die frühere `TommiG1/HA_VAG-EU-Data-Act`-Integration liefert
   diese nicht mehr)
-- Standort (`STANDORT_TRACKER`, ein `device_tracker`) und Batteriespannung
-  (`BATTERIE_SENSOR`) — vom FMM003, z. B. `device_tracker.<gerätename>`
+- Standort (`STANDORT_LAT_SENSOR`/`STANDORT_LON_SENSOR`, zwei eigene
+  `sensor`-Entities für Breiten-/Längengrad — flespi liefert Koordinaten so,
+  nicht als `latitude`/`longitude`-Attribute eines `device_tracker`) und
+  Batteriespannung (`BATTERIE_SENSOR`) — vom FMM003, z. B.
+  `sensor.<gerätename>_latitude_coordinate_value`/`..._longitude_coordinate_value`
   bzw. `sensor.<gerätename>_external_power_voltage` (**nicht**
   `..._battery_voltage` — das ist die interne Pufferzelle des Trackers,
   nicht die Fahrzeugbatterie)