Introduce the producer-facing half of the mission repair feed: a global
bounded (8192) channel carrying lightweight MrfIntent values from IO
error paths, plus the RUSTFS_HEAL_MRF_ENABLE delivery kill-switch and
config constants for queue/journal sizing. Delivery is strictly
non-blocking (try_send, drop-on-full) so it can sit on decode-failure
and partial-write paths without adding latency. HealRequestSource grows
a 'mrf' variant so admission accounting can attribute replayed intents.
Part of backlog#1865 (option a: wire HealEvent-style intents with a
durable retry ledger).
Co-Authored-By: heihutu <heihutu@gmail.com>
houseme
f477d27861