Phase 3 Stream A: Rust's prop-grid-rs writes f00 profile files as
MessagePack (c4f309c). Elixir needs to read both formats during the
cutover window and indefinitely afterward — .mp.gz wins when both
exist.
Reader:
- path_for/1 stays on .etf.gz (Elixir legacy writer)
- mp_path_for/1 returns the .mp.gz sibling Rust lands
- read/1 prefers .mp.gz, falls back to .etf.gz, :enoent if neither
- decode_mp_body handles the top-level {v, valid_time, cells} shape
- normalize_profile atomizes a whitelist of known keys (surface_*,
native_min_gradient, ducts[], profile[] levels, ...) and leaves
everything else as strings so no String.to_atom bomb is possible
- Directory scan picks up both extensions so retain_window and
prune_older_than also work uniformly; list_valid_times dedupes
by timestamp
Adds msgpax ~> 2.4 dependency. 4 new tests cover format preference,
key atomization, :enoent path, and dedupe.
Graham McIntire
d41ced5850