feat(ecstore): type internode client-acquisition failures for quorum buckets (#6619)

* feat(ecstore): type internode client-acquisition failures for stable quorum buckets

Backlog#1845 step 3, first typed family. The largest other(format!) message family in ecstore was 'can not get client, err: {detail}' (~50 production sites): every internode RPC that fails to acquire a client wrapped the dial/auth error with per-peer detail into DiskError::other / StorageError::other, whose Io equality compares the rendered message. N disks failing for this same cause therefore counted as N distinct errors in reduce_errs, starving quorum aggregation, and remote_disk call sites double-wrapped the message on top of get_client's own wrap.

Introduce DiskError::RemoteClientUnavailable(String) (wire code 0x2B) and its StorageError twin (StorageErrorCode 0x54): equality and hashing use the wire code alone, so same-cause failures land in one quorum bucket regardless of per-peer detail, while Display keeps the detail so substring classifiers (network needles, heal recoverability) keep reading it unchanged. Wire encoding carries the rendered detail in error_info and decode restores the typed variant; old peers fall back to the legacy string form gracefully.

Call sites: remote_disk get_client/get_bulk_client/offline-bypass/recovery-probe now construct the typed variant and the ~60 redundant double-wrap map_errs are gone; peer_rest_client's three client getters and offline gates, peer_s3_client, and admin_server_info follow. The tier-config-reload connection classifier's anchored 'can not get client' substring check becomes a typed match on the variant (the string form is retired and now classifies as Terminal, pinned by test).

Ref rustfs/backlog#1845

* chore(ci): refresh error other ratchet baseline

* fix(ecstore): classify typed client network failures

crates/storage-api/src/error.rs

@@ -104,6 +104,7 @@ pub enum StorageErrorCode {
     Timeout,
     InvalidPath,
     QuotaExceeded,
+    RemoteClientUnavailable,
 }
 
 impl StorageErrorCode {
@@ -190,6 +191,7 @@ impl StorageErrorCode {
             Self::Timeout => 0x51,
             Self::InvalidPath => 0x52,
             Self::QuotaExceeded => 0x53,
+            Self::RemoteClientUnavailable => 0x54,
         }
     }
 
@@ -276,6 +278,7 @@ impl StorageErrorCode {
             0x51 => Some(Self::Timeout),
             0x52 => Some(Self::InvalidPath),
             0x53 => Some(Self::QuotaExceeded),
+            0x54 => Some(Self::RemoteClientUnavailable),
             _ => None,
         }
     }
@@ -351,6 +354,7 @@ mod tests {
         (StorageErrorCode::OperationCanceled, 0x41),
         (StorageErrorCode::NamespaceLockQuorumUnavailable, 0x42),
         (StorageErrorCode::QuotaExceeded, 0x53),
+        (StorageErrorCode::RemoteClientUnavailable, 0x54),
     ];
 
     const DISK_PRESERVATION_ERROR_CODES: &[(StorageErrorCode, u32)] = &[