MrmsFetchWorker fired every 2 min on the :propagation queue, decoding an
MRMS PrecipRate GRIB2 into MrmsCache. Its only consumer,
AsosAdjustmentWorker, is disabled in all configs (dev / config / runtime).
Net effect: 30 GRIB2 decodes/hour of dead work on hot pods.
Removed:
- MrmsFetchWorker, MrmsClient, MrmsCache and their tests
- cron entries in config.exs, dev.exs, runtime.exs
- mrms_req_options stub in test.exs
- MrmsCache from supervision tree in application.ex
- stale MRMS references in PropagationGridWorker docstring and test
Also adds docs/plans/2026-04-19-rust-migration-phase3.md which tracks
the broader Stream A (f00 port) and Stream C (HrrrFetchWorker port)
follow-on work.