refactor(heal): classify recoverability typed-first with documented needle fallback
Backlog#1845 step 6. Heal's retry decision leaned on substring matching of rendered messages; the typed information available in the error values now takes priority:
- Lock failures classify by LockError's own taxonomy instead of the blanket Lock(_) => recoverable: fatal variants (ResourceNotFound / PermissionDenied / Configuration) are terminal since retrying cannot fix them, while contention and transport variants (Timeout, Network, Internal, AlreadyLocked, QuorumNotReached, InsufficientNodes, ...) stay recoverable exactly as before.
- DiskError::RemoteClientUnavailable and its StorageError twin (typed in #6619) join the typed recoverable lists, so client-acquisition failures no longer depend on which needle happens to appear in the detail.
- task.rs is_transient_lock_or_timeout_error consults LockError::is_retryable / QuorumNotReached and the typed Timeout variants before falling back to needles.
- The substring list is demoted to a documented fallback: every needle now carries a producer census comment naming what emits it, with the shrink-only rule stated (delete the needle when its producer becomes typed end-to-end). heal rename incomplete remains the one needle with no typed producer.
heal gains a direct rustfs-lock dependency (already transitive via ecstore) to name LockError variants.
New tests pin each typed source: contention/transport lock variants recoverable, fatal lock variants terminal, RemoteClientUnavailable recoverable with a detail that avoids every needle. All existing recoverability tests stay green.
Ref rustfs/backlog#1845
heal::Error carried six variants with zero construction and zero match sites (ConfigurationError, NotFound, TaskAlreadyExists, ManagerNotRunning, EventProcessingFailed, ProgressTrackingFailed) plus IO(String), which was never constructed either — its only appearances were two or-pattern match arms that could never fire (task.rs's demotion match and the recoverability classifier). All seven are deleted and the two or-patterns lose their dead alternative.
Config(String) stays (live, four construction sites); Io(std::io::Error) stays; the retry classifier's behavior is untouched per the issue constraint — removing an arm that can never match is not a classification change.
Ref rustfs/backlog#1831 (PR3).
Co-authored-by: cxymds <cxymds@gmail.com>
Co-authored-by: houseme <housemecn@gmail.com>
Zhengchao An