The 18-hour forecast chart on /path now shows the same weighted-
criteria panel the /map popup builds when the user clicks a grid
cell. Hovering a dot fires a server roundtrip that fetches
Propagation.point_detail at the path's midpoint for that valid_time;
results are cached client-side so re-hovering is instant.
`Propagation.point_detail/4` now returns a `:profile_source` tag —
`:exact`, `{:fallback, fallback_valid_time}`, or `:unavailable` —
distinguishing real per-hour breakdowns (Rust pipeline writes a
profile file for every f00..f18 step) from rare cycle-miss fallbacks
where we approximate from a recent analysis profile. Stale comment
about "only f00 persists profiles" updated.
Map utilities (FACTOR_META, FACTOR_ORDER, factorBar,
factorExplanation, scoreTier, FactorMeta, ScoreTier) are now exported
from propagation_map_hook so the new path hook reuses the exact same
look + copy.
