Aliases: add module aliases for 9 nested module references
Apply: replace apply/3 with direct module attribute calls
Line length: break 1 long spec line
Refactoring: extract helpers to reduce complexity and nesting
in show.ex, radio.ex, weather workers, terrain, duct detection,
backfill dashboard, contact map, and mix tasks
- HrrrClient.hrrr_url accepts forecast_hour param (wrfsfcfHH.grib2)
- PropagationGridWorker fetches all 19 forecast hours per run
- Propagation.scores_at/3 queries scores at specific valid_time
- Propagation.available_valid_times/1 returns all forecast times for timeline
- Pruning keeps scores with valid_time >= now - 2h (forecast-aware)
- MapLive: select_time event, timeline data pushed to JS
- JS: forecast timeline bar at bottom of map with clickable hour buttons
- PubSub broadcast sends list of valid_times instead of single time
