fix(site-replication): stamp replicated bucket configs with the source updated_at (backlog#2292)

The bucket-meta receiver judged an incoming item stale by comparing its
source `updated_at` with the `*_config_updated_at` stamp of the config on
disk, but that stamp was the receiver's local clock at apply time
(`BucketMetadata::update_config`). A source edit newer than the applied one
but delivered after the local stamp was judged stale and acknowledged with
200: two quick source edits under delivery delay lose the second, and a peer
clock ahead of ours loses every follow-up edit inside the skew.

Add explicit-timestamp write entries, expanding rather than changing the
existing ones:

- `BucketMetadata::update_config_at`; `update_config` delegates to it with
  the local clock.
- `metadata_sys::update_if_incarnation_at`,
  `update_under_transaction_lock_at`, `update_quota_if_incarnation_at`,
  threaded through the shared write-guard path as `Option<OffsetDateTime>`
  (`None` keeps local stamping for every existing caller and for deletes).
- Re-exported through the ecstore `api` facade and the rustfs admin
  `storage_api::metadata_sys` facade.

`apply_bucket_meta_item` now persists policy, tags, versioning, object-lock,
sse, replication, quota and cors configs with the item's source time, so the
stored stamp equals the source `updatedAt` and staleness is judged source
time against source time. Items without `updated_at` keep the local stamp.
lc-config stays on the local stamp: its staleness axis is the in-document
`expiry_updated_at` the merge records, and the whole-config time only serves
as its deletion / legacy lower bound. Local (non-replicated) edits keep
stamping the local clock — they are the source.

(cherry picked from commit c1009c018b217ef9edc7773c8e56667ea7e77335)

crates/ecstore/src/api/mod.rs

@@ -204,8 +204,9 @@ pub mod bucket {
             get_public_access_block_config, get_quota_config, get_replication_config, get_request_payment_config, get_sse_config,
             get_tagging_config, get_versioning_config, get_website_config, init_bucket_metadata_sys, list_bucket_targets,
             reload_bucket_metadata, remove_bucket_metadata, set_bucket_metadata, update,
-            update_bucket_targets_under_transaction_lock, update_config_with, update_if_incarnation, update_quota_if_incarnation,
-            update_under_transaction_lock,
+            update_bucket_targets_under_transaction_lock, update_config_with, update_if_incarnation, update_if_incarnation_at,
+            update_quota_if_incarnation, update_quota_if_incarnation_at, update_under_transaction_lock,
+            update_under_transaction_lock_at,
         };
     }