mount: carry an alias unlink's stored entry into the open handle

Removing one of several hard links lowers the stored link count and
stamps a new ctime, and the handle may still hold the removed name. Look up
the entry at the name the handle flushes through and adopt it, so the next
content flush matches the stored entry, writes the right count, and
attribute saves address the surviving name.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

weed/mount/weedfs_file_mkrm.go

@@ -1,6 +1,7 @@
 package mount
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"syscall"
@@ -358,9 +359,14 @@ func (wfs *WFS) Unlink(cancel <-chan struct{}, header *fuse.InHeader, name strin
 	}
 
 	// Another link still names the inode, so its open handle keeps flushing
-	// through that name.
+	// through that name, over the count and ctime the filer stored there.
 	if isHardLink && markedInode != 0 {
-		if _, status := wfs.inodeToPath.GetPath(markedInode); status == fuse.OK {
+		if survivor, status := wfs.inodeToPath.GetPath(markedInode); status == fuse.OK {
+			if fh, found := wfs.fhMap.FindFileHandle(markedInode); found {
+				if stored, tsNs, signature, err := filer_pb.GetEntry(ctx, wfs, survivor); err == nil && bytes.Equal(stored.GetHardLinkId(), entry.HardLinkId) {
+					fh.adoptLinkChange(stored, tsNs, signature)
+				}
+			}
 			wfs.clearHandleDeleted(markedInode, deleteEpoch)
 		}
 	}