fix(ec): blanket-clean every destination over the full shard range (#9512)

* fix(ec): blanket-clean every destination over the full shard range

The previous cleanup pass walked t.sources only, with the shard ids the
topology had reported at detection time. In the wild, a destination can
end up with EC shards mounted that the topology snapshot didn't list —
shards on a sibling disk that hadn't heartbeated, or shards left over
from a concurrent attempt's mount step. FindEcVolume still returns
true, so the next ReceiveFile trips the mounted-volume guard.

Cleanup now unions t.sources (with ShardIds) and t.targets and issues
unmount + delete over [0..totalShards-1] on each. Both RPCs are
idempotent on missing shards, so the wider sweep is free.

Two new tests cover the gap: shards mounted beyond what t.sources
lists, and a target-only destination with no source row.

* log(ec): include disk_id in EC unmount/delete/refusal log lines

The current logs identify the volume and shard but leave disk_id off,
which makes the cross-server cleanup story hard to follow when
multiple disks of one server hold pieces of the same volume:

  UnmountEcShards 4121.1                              -> add disk_id
  ec volume video-recordings_4121 shard delete [1 5]  -> add per-loc disk_id
  volume server X:Y deletes ec shards from 4121 [...] -> add disk_id
  ReceiveFile: ec volume 4121 is mounted; refusing... -> add disk_ids

ReceiveFile's refusal now names the disk_ids actually holding the
mount so operators can see whether the next cleanup pass needs to
target a sibling disk. Added Store.FindEcVolumeDiskIds /
Store::find_ec_volume_disk_ids as the supporting primitive.

Mirrored in seaweed-volume/src/ (unmount log in Store::unmount_ec_shard,
heartbeat delete log in diff_ec_shard_delta_messages, refusal in the
ReceiveFile handler).

* test(ec): stub VolumeEcShardsUnmount/Delete on the fake volume server

The plugin-worker EC tests boot a fake volume server that embeds
UnimplementedVolumeServerServer. After the worker started calling
VolumeEcShardsUnmount + VolumeEcShardsDelete pre-distribute, the
default Unimplemented response surfaced as fourteen "method not
implemented" errors and TestErasureCodingExecutionEncodesShards
failed. Both RPCs are no-ops here — nothing on the fake server has
mounted state or persisted shard files to remove.

seaweed-volume/src/server/grpc_server.rs

@@ -1511,9 +1511,11 @@ impl VolumeServer for VolumeGrpcService {
                             // EcVolume holds fds on the same inodes, so overwriting
                             // corrupts live readers.
                             if store.has_ec_volume(VolumeId(info.volume_id)) {
+                                let mounted_disks =
+                                    store.find_ec_volume_disk_ids(VolumeId(info.volume_id));
                                 resp_error = Some(format!(
-                                    "ec volume {} is mounted; unmount before ReceiveFile",
-                                    info.volume_id
+                                    "ec volume {} is mounted on disk_ids:{:?}; unmount before ReceiveFile",
+                                    info.volume_id, mounted_disks
                                 ));
                                 break;
                             }

seaweed-volume/src/server/heartbeat.rs

@@ -344,6 +344,12 @@ fn diff_ec_shard_delta_messages(
         if !current.contains_key(key) {
             let mut deleted = message.clone();
             deleted.shard_sizes = vec![0];
+            tracing::info!(
+                volume_id = deleted.id,
+                disk_id = deleted.disk_id,
+                ec_index_bits = deleted.ec_index_bits,
+                "deletes ec shards"
+            );
             deleted_ec_shards.push(deleted);
         }
     }