Resolve all 46 low-severity architecture review findings

src/ZB.MOM.WW.ScadaBridge.KpiHistory/KpiHistoryOptions.cs

@@ -16,6 +16,9 @@ public sealed class KpiHistoryOptions
     /// </summary>
     public TimeSpan SampleInterval { get; set; } = TimeSpan.FromSeconds(60);
 
+    /// <summary>Maximum wait for one KPI source (default 10 seconds). Unfinished sources remain owned and are skipped on later ticks.</summary>
+    public TimeSpan SourceTimeout { get; set; } = TimeSpan.FromSeconds(10);
+
     /// <summary>
     /// Central retention window in days for recorded KPI samples (default 90,
     /// range <c>[1, 3650]</c>). Rows older than this are dropped by the purge