fix(scanner): discover sub-quorum heal candidates (#6384)

* fix(scanner): preserve unversioned heal retries

* fix(scanner): bound orphan heal discovery fallback

* fix(filemeta): fence unsafe heal key components

* fix(scanner): preserve exact overflow heal versions

---------

Co-authored-by: houseme <housemecn@gmail.com>

crates/scanner/src/scanner_folder/item_actions.rs

@@ -13,6 +13,8 @@
 // limitations under the License.
 /// Per-object scan actions: ScannerItem, the get-size failure policy, and the heal/ILM admission helpers.
 use super::*;
+#[cfg(test)]
+use rustfs_filemeta::MetadataResolutionParams;
 
 /// Cached folder information for scanning
 #[derive(Clone, Debug)]
@@ -89,6 +91,22 @@ pub(super) fn build_object_heal_request(
     }
 }
 
+/// Build the versionless inspection request used when discovery cannot prove
+/// a destructive version identity (for example an unversioned object or a
+/// bounded candidate overflow). The explicit flag is the fail-closed safety
+/// boundary; callers must not reconstruct it with the destructive default.
+pub(super) fn build_non_destructive_object_heal_request(
+    bucket: String,
+    object: String,
+    scan_mode: HealScanMode,
+    priority: HealChannelPriority,
+) -> HealChannelRequest {
+    let mut request = build_object_heal_request(bucket, object, None, scan_mode, priority);
+    request.remove_corrupted = Some(false);
+    request
+}
+
+#[cfg(test)]
 pub(super) fn resolve_object_heal_entry(
     entries: &MetaCacheEntries,
     resolver: MetadataResolutionParams,