cleanup: drop coord backfill, drop transit overlay, block PM autofill

- Remove the admin "Koordinaten nachladen" button, /actions/backfill-coords
  endpoint, geocode.py, googlemaps dep, GMAPS_API_KEY plumbing in the web
  service, and the map diagnostic line. Going-forward geocoding happens in
  alert on scrape; upsert_flat backfill on re-submit remains for edge cases
- Remove the OpenRailwayMap transit overlay (visually noisy); keep CartoDB
  Voyager as the sole basemap
- Profile + notifications forms get autocomplete="off" + data-lpignore +
  data-1p-ignore at form and field level to keep password managers from
  popping open on /einstellungen; immomio_password uses autocomplete=new-password

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/settings.py

@@ -63,6 +63,3 @@ SMTP_STARTTLS: bool = getenv("SMTP_STARTTLS", "true").lower() in ("true", "1", "
 
 # --- App URL (used to build links in notifications) ---------------------------
 PUBLIC_URL: str = getenv("PUBLIC_URL", "https://flat.lab.moritz.run")
-
-# --- Google Maps (used for one-shot coord backfill via admin action) ----------
-GMAPS_API_KEY: str = getenv("GMAPS_API_KEY", "")