The contact detail page used to gather every enrichment source in one
parallel_hydrate/2 bundle and await all five tasks before updating any
assigns, so users watched the whole right-hand column flash in at the
speed of the slowest query (usually hrrr_profiles_for_path against a
42M-row table).
Each source now runs in its own start_async task: :weather, :solar,
:hrrr_path, :terrain, :iemre. Matching handle_async/3 clauses assign
the slot and call refresh_computed/1, which rebuilds elevation_profile
+ propagation_analysis + data_sources from whatever's currently in
assigns. Sections appear independently as their data arrives, and the
existing PubSub handlers (:hrrr_ready, :weather_ready, :terrain_ready,
:solar_ready) still pick up later backfill completions the same way
they did before.