v0.8.1 — dedupe road condition sensors

Fixes a unique-ID collision on the road condition sensors: Travel-IQ feeds (e.g. Wisconsin) return several readings per roadway, and the duplicate rows produced the same unique_id so HA dropped the extras at setup with 'Platform the511 does not generate unique IDs' errors. select_road_conditions now collapses readings by road name (first wins) before the sort-and-cap.