fix(site-event-logging): resolve SiteEventLogging-005,007,008,010 — background async writer, drop concrete downcast, surface write failures, test coverage

src/ScadaLink.SiteEventLogging/EventLogQueryService.cs

@@ -18,11 +18,14 @@ public class EventLogQueryService : IEventLogQueryService
     private readonly ILogger<EventLogQueryService> _logger;
 
     public EventLogQueryService(
-        ISiteEventLogger eventLogger,
+        SiteEventLogger eventLogger,
         IOptions<SiteEventLogOptions> options,
         ILogger<EventLogQueryService> logger)
     {
-        _eventLogger = (SiteEventLogger)eventLogger;
+        // Depend on the concrete recorder directly: queries must funnel database
+        // access through its lock-guarded WithConnection. Taking ISiteEventLogger and
+        // downcasting would throw InvalidCastException for any other implementation.
+        _eventLogger = eventLogger;
         _options = options.Value;
         _logger = logger;
     }