feat(ecstore,scanner): deliver MRF intents from error paths (HS-01)

Wire the three production delivery points, each a single non-blocking
try_send next to the existing in-memory heal paths, which stay as the
fast path:

- read.rs decode-error branch: DecodeFailure intent beside the existing
  read-repair submit, so an Urgent ECDecode request survives restarts
  even when the Low-priority read-repair request was dropped or lost.
- add_partial: PartialWrite intent, giving partial-write recovery a
  durable Normal-priority object heal across restarts.
- scanner_folder metadata-corruption classification: MetadataCorruption
  intent beside the existing High-priority scanner heal request.

All three are on error paths only: zero cost on healthy IO.

Part of backlog#1865 (option a).

Co-Authored-By: heihutu <heihutu@gmail.com>

crates/ecstore/src/set_disk/ops/object.rs

@@ -5845,6 +5845,14 @@ impl crate::storage_api_contracts::object::ObjectOperations for SetDisks {
 
     #[tracing::instrument(skip(self))]
     async fn add_partial(&self, bucket: &str, object: &str, version_id: &str) -> Result<()> {
+        // MRF journal intent: partial-write recovery must survive a restart
+        // (HS-01); the heal request below remains the in-memory fast path.
+        rustfs_common::mrf_channel::try_send_mrf_intent(
+            rustfs_common::mrf_channel::MrfKind::PartialWrite,
+            bucket,
+            object,
+            uuid::Uuid::try_parse(version_id).ok(),
+        );
         let mut request = rustfs_common::heal_channel::create_heal_request_with_options(
             bucket.to_string(),
             Some(object.to_string()),

crates/ecstore/src/set_disk/read.rs

@@ -1077,6 +1077,15 @@ impl SetDisks {
                             "Recoverable decode error triggered read repair"
                         );
                         let version_id = fi.version_id.as_ref().map(ToString::to_string);
+                        // MRF journal intent: keeps a durable Urgent ECDecode
+                        // request alive across restarts even when the in-memory
+                        // read-repair request is dropped or lost (HS-01).
+                        rustfs_common::mrf_channel::try_send_mrf_intent(
+                            rustfs_common::mrf_channel::MrfKind::DecodeFailure,
+                            bucket,
+                            object,
+                            fi.version_id,
+                        );
                         submit_read_repair_heal(
                             bucket,
                             object,

crates/scanner/src/scanner_folder.rs

@@ -2187,6 +2187,15 @@ impl FolderScanner {
                         }
 
                         if let GetSizeFailureAction::HealMetadata { object } = failure_action {
+                            // MRF journal intent: durable High-priority Metadata
+                            // heal across restarts (HS-01); the scanner heal
+                            // request below stays as the immediate path.
+                            rustfs_common::mrf_channel::try_send_mrf_intent(
+                                rustfs_common::mrf_channel::MrfKind::MetadataCorruption,
+                                &item.bucket,
+                                &object,
+                                None,
+                            );
                             self.send_required_scanner_heal_request(
                                 PendingScannerHealKind::Object,
                                 item.bucket.clone(),