fix(site-event-logging): resolve SiteEventLogging-006,009,011 — severity index, accurate XML doc, dead-placeholder removal

src/ScadaLink.SiteEventLogging/ISiteEventLogger.cs

@@ -6,14 +6,20 @@ namespace ScadaLink.SiteEventLogging;
 public interface ISiteEventLogger
 {
     /// <summary>
-    /// Record an event asynchronously.
+    /// Record an event asynchronously. The call enqueues the event onto a background
+    /// writer and returns without blocking the caller on disk I/O. The returned
+    /// <see cref="Task"/> completes once the event is durably persisted and faults if
+    /// the write fails, so callers that <c>await</c> it observe success or failure.
     /// </summary>
     /// <param name="eventType">Category: script, alarm, deployment, connection, store_and_forward, instance_lifecycle</param>
     /// <param name="severity">Info, Warning, or Error</param>
     /// <param name="instanceId">Optional instance ID associated with the event</param>
     /// <param name="source">Source identifier, e.g., "ScriptActor:MonitorSpeed"</param>
     /// <param name="message">Human-readable event description</param>
-    /// <param name="details">Optional JSON details (stack traces, compilation errors, etc.)</param>
+    /// <param name="details">
+    /// Optional free-form detail text (stack traces, compilation errors, etc.).
+    /// Stored verbatim — JSON is conventional but not validated or enforced.
+    /// </param>
     Task LogEventAsync(
         string eventType,
         string severity,