feat(scanner): emit excess alerts as S3 notification events (HS-04) (#6176)

* feat(scanner): emit excess alerts as S3 notification events

The excess-versions / excess-version-size / excess-folders alerts were
metrics-and-logs only; consoles and external auditors had no way to hear
them (rustfs/backlog#1868, HS-04). MinIO emits s3:ObjectManyVersions /
s3:ObjectLargeVersions / s3:PrefixManyFolders for the same conditions —
RustFS carries those as EventName::Scanner* with s3:Scanner:* wire names
that already existed unpublished.

The three alert sites now also dispatch through the standard event
pipeline (send_event via the storage_api owner facade), carrying the
actual values and thresholds in req_params and UserAgent "Scanner".
Without a cooldown a single over-threshold object would re-emit on every
~60s scan cycle, so emissions are edge-held per (kind, bucket, object)
for 24h (RUSTFS_SCANNER_ALERT_COOLDOWN_SECS, 0 = every cycle), backed by
a process-global map with a 4096-key hard cap that clears rather than
grows. Metrics and structured logs stay level-triggered every cycle;
only the notification events are held back. A restart resets the
cooldown deliberately: one re-emission per still-hot key buys back
visibility after the restarts that accompany incident response.

Tests pin the edge-hold semantics (first fires, immediate re-check held,
independent keys, cooldown expiry re-fires, zero cooldown always emits,
hard bound) in one sequential test for the process-global map, and pin
the emitted wire names against EventName's canonical string forms so a
subscribed bucket notification can never silently stop matching.
docs/operations/scanner-excess-alerts.md documents the three events,
the metric-vs-event cadence difference, and the HS-15 threshold deltas
(alert_excess_folders 65538 vs MinIO 50000 is deliberate: Proxmox
Backup Server chunk layout compatibility).

Closes rustfs/backlog#1868.

Co-Authored-By: heihutu <heihutu@gmail.com>

* docs(operations): split scanner excess alerts into English and Chinese pages

The page shipped Chinese-only; keep it as scanner-excess-alerts_zh.md and
add a faithful English translation at the original path, cross-linked at
the top of both.

Co-Authored-By: heihutu <heihutu@gmail.com>

---------

Co-authored-by: heihutu <heihutu@gmail.com>

crates/scanner/src/storage_api.rs

@@ -78,6 +78,7 @@ pub(crate) use rustfs_ecstore::api::disk::{
 pub(crate) use rustfs_ecstore::api::error::{
     Error as EcstoreErrorType, Result as EcstoreResultType, StorageError as EcstoreStorageError,
 };
+pub(crate) use rustfs_ecstore::api::event::{EventArgs as EcstoreEventArgs, send_event as ecstore_send_event};
 #[cfg(test)]
 pub(crate) use rustfs_ecstore::api::layout::{
     EndpointServerPools as EcstoreEndpointServerPools, Endpoints as EcstoreEndpoints, PoolEndpoints as EcstorePoolEndpoints,
@@ -110,8 +111,8 @@ pub(crate) mod owner {
         ECSTORE_BUCKET_META_PREFIX, ECSTORE_RUSTFS_META_BUCKET, ECSTORE_STORAGE_FORMAT_FILE, ECSTORE_STORAGECLASS_RRS,
         ECSTORE_STORAGECLASS_STANDARD, ECSTORE_TRANSITION_COMPLETE, EcstoreBucketTargetSys, EcstoreBucketVersioningSys,
         EcstoreDisk, EcstoreDiskAPI, EcstoreDiskBytes, EcstoreDiskError, EcstoreDiskInfo, EcstoreDiskInfoOptions,
-        EcstoreDiskLocation, EcstoreDiskResult, EcstoreErrorType, EcstoreEvaluator, EcstoreEvent, EcstoreLcEventSrc,
-        EcstoreLifecycle, EcstoreListPathRawOptions, EcstoreNsScannerOpenRequest, EcstoreObjectOpts,
+        EcstoreDiskLocation, EcstoreDiskResult, EcstoreErrorType, EcstoreEvaluator, EcstoreEvent, EcstoreEventArgs,
+        EcstoreLcEventSrc, EcstoreLifecycle, EcstoreListPathRawOptions, EcstoreNsScannerOpenRequest, EcstoreObjectOpts,
         EcstoreReplicationConfigurationExt, EcstoreReplicationScannerBridge, EcstoreResultType, EcstoreScanGuard,
         EcstoreSetDisks, EcstoreStorageError, EcstoreStore, EcstoreTierConfig, EcstoreVersioningApi,
         ScannerReplicationHealObject, ScannerReplicationHealResult, ScannerReplicationQueueAdmission, ecstore_apply_expiry_rule,
@@ -121,7 +122,7 @@ pub(crate) mod owner {
         ecstore_is_erasure_sd, ecstore_is_reserved_or_invalid_bucket, ecstore_list_path_raw,
         ecstore_object_opts_from_object_info, ecstore_path2_bucket_object, ecstore_path2_bucket_object_with_base_path,
         ecstore_read_config, ecstore_replace_bucket_usage_memory_from_info, ecstore_resolve_object_store_handle,
-        ecstore_save_config, scanner_replication_config_for_lifecycle_eval,
+        ecstore_save_config, ecstore_send_event, scanner_replication_config_for_lifecycle_eval,
     };
 
     #[cfg(test)]