feat(audit): archive retention and superseded stale-archive cleanup (ScadaBridge#109)

Owner decisions recorded: the archive destination stays a directory/UNC
(no object-storage client; share + permissions named at enablement),
parquet-tools-only reading (no re-import), unsigned like the chain (#107).

AuditLog:Archive:RetentionDays (default 0 = never delete; else must exceed
AuditLog:RetentionDays, counted from the archived month's end) and
DeleteSupersededStaleArchives (default true) run after every purge tick.
A retried purge's stale Archived archive is deleted only when a later,
verifying, Purged archive of the same partition provably holds every row:
same prior anchor and the stale chain-end hash at its chain-end sequence
(row or tombstone), every unchained row present by EventId; otherwise it is
reported KeptStale. A sole copy left at Archived is never touched. Deletion
removes only the archive name's own three files in its folder, manifest
first, never a manifest-supplied path. `audit archive cleanup [--dry-run]`
= CleanupAuditArchives (Administrator).

AuditLogArchiveCleanupTests (MSSQL) cover retried purge, kept stale copy,
sole copy, retention and the path guard; each safety rule mutation-checked.
Follow-ups filed: #113, #114, #115.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

src/ZB.MOM.WW.ScadaBridge.ManagementService/ManagementEndpoints.cs

@@ -69,6 +69,8 @@ public static class ManagementEndpoints
         // AuditLog archive verification (ScadaBridge#42) hashes and re-chains a whole month's
         // Parquet archive.
         typeof(VerifyAuditArchiveCommand),
+        // Archive cleanup proves stale archives redundant by reading Parquet files (ScadaBridge#109).
+        typeof(CleanupAuditArchivesCommand),
     ];
 
     /// <summary>