Resolve all 46 low-severity architecture review findings

src/ZB.MOM.WW.ScadaBridge.AuditLog/Central/AuditLogPurgeOptions.cs

@@ -30,13 +30,16 @@ public sealed class AuditLogPurgeOptions
     /// <summary>Period of the purge tick in hours (default 24).</summary>
     public int IntervalHours { get; set; } = 24;
 
+    /// <summary>Maximum rows deleted for each channel in one purge tick (default 50,000); remaining backlog resumes on later ticks.</summary>
+    public int MaxPurgedRowsPerChannelPerTick { get; set; } = 50_000;
+
     /// <summary>
     /// Batch size for the per-channel retention-override row DELETE
     /// (<see cref="ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Repositories.IAuditLogRepository.PurgeChannelOlderThanAsync"/>).
     /// Each <c>DELETE TOP (@batch)</c> caps the transaction-log and lock footprint
-    /// per statement; the repository loops batches until no rows remain. Default
-    /// 5000 keeps individual deletes short on a busy central DB while still draining
-    /// a large backlog within a tick. Clamped to a sane minimum in
+    /// per statement; the repository stops at <see cref="MaxPurgedRowsPerChannelPerTick"/>
+    /// so a backlogged channel yields to later channels. Default 5000 keeps individual
+    /// deletes short on a busy central DB. Clamped to a sane minimum in
     /// <see cref="ChannelPurgeBatchSize"/>.
     /// </summary>
     /// <remarks>