feat(trips): add --skip-geocode flag to backfill script

The historical trips table is much larger than the spec assumed (7,634
rows on prod, not the 8 the CLAUDE.md snapshot suggested). Reverse-geocoding
all of them via Nominatim's 1 req/sec TOS throttle would take ~4¼ hours
end-to-end.

--skip-geocode bypasses the Nominatim calls entirely. Geometry, plate, and
idle backfills run in minutes; addresses stay NULL on historical rows and
will only be populated for future trips by poll_trips.

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

backfill_trips_enrichment.py

@@ -27,6 +27,12 @@ Usage:
 
     # Limit to trips since a date (UTC)
     python backfill_trips_enrichment.py --since 2026-04-01 --apply
+
+    # Skip Nominatim reverse-geocoding (geometry/plate/idle only — runs in
+    # minutes instead of hours when backfilling thousands of rows). Addresses
+    # remain NULL for these rows and will be filled by future poll_trips
+    # cycles only for new trips, not retroactively.
+    python backfill_trips_enrichment.py --skip-geocode --apply
 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
 """
 
@@ -100,9 +106,12 @@ def _load_plates_cache(cur) -> dict[str, str]:
     return {imei: plate for imei, plate in cur.fetchall()}
 
 
-def run(apply: bool, filter_imei: str | None, since: str | None) -> None:
+def run(apply: bool, filter_imei: str | None, since: str | None,
+        skip_geocode: bool = False) -> None:
     t0 = time.time()
     enriched = degenerate = no_fixes = failed = 0
+    if skip_geocode:
+        log.info("Reverse-geocoding disabled (--skip-geocode). Addresses will stay NULL.")
 
     with get_conn() as conn:
         with conn.cursor() as cur:
@@ -149,6 +158,9 @@ def run(apply: bool, filter_imei: str | None, since: str | None) -> None:
                             trip_id, imei, waypoints_count,
                         )
 
+                    if skip_geocode:
+                        start_address = end_address = None
+                    else:
                         start_address = reverse_geocode(start_lat, start_lng)
                         end_address   = reverse_geocode(end_lat, end_lng)
                     vehicle_plate = existing_plate or plates.get(imei)
@@ -210,6 +222,8 @@ if __name__ == "__main__":
     parser.add_argument("--apply",        action="store_true", help="Write changes to DB (default: dry-run)")
     parser.add_argument("--imei",         default=None,        help="Limit to a single IMEI")
     parser.add_argument("--since",        default=None,        help="Only trips with start_time >= YYYY-MM-DD (UTC)")
+    parser.add_argument("--skip-geocode", action="store_true", help="Skip Nominatim reverse-geocoding (fast path for large backfills)")
     args = parser.parse_args()
 
-    run(apply=args.apply, filter_imei=args.imei, since=args.since)
+    run(apply=args.apply, filter_imei=args.imei, since=args.since,
+        skip_geocode=args.skip_geocode)