Two wins in the /map hot path.
1. preload_forecast fired on every Leaflet moveend — which arrives in
bursts during pan/zoom — and each firing read + filtered + shipped
18 forecast-hour score lists (up to 90k cells per hour at full
CONUS view) over the LiveView websocket. Now debounced to the
trailing edge: the user must stop moving for 750 ms before we pay
the preload cost. select_band and propagation_updated go through
the same scheduler so a storm of PubSub updates during an hourly
chain also coalesces.
2. ScoreCache.grid_to_filtered_list walked the 92k-cell grid twice
(Enum.filter then Enum.map) and allocated an intermediate tuple
list between them. Enum.reduce emits only in-bounds result maps
directly — halves map traversal + drops the tuple intermediate.
Graham McIntire
aebf3911ce