Match Go readSuperBlock: propagate replication parse errors

Go returns an error when parsing the replication string from the .vif
file fails. Rust was silently ignoring the parse failure and using the
super block's replication as-is.

seaweed-volume/src/storage/volume.rs

@@ -951,9 +951,8 @@ impl Volume {
 
         // Match Go: if volumeInfo.Replication is set, override super block's ReplicaPlacement
         if !self.volume_info.replication.is_empty() {
-            if let Ok(rp) = ReplicaPlacement::from_string(&self.volume_info.replication) {
-                self.super_block.replica_placement = rp;
-            }
+            let rp = ReplicaPlacement::from_string(&self.volume_info.replication)?;
+            self.super_block.replica_placement = rp;
         }
 
         Ok(())