refactor(time): change DateTime from UTC to local time

- Change HealthCheckHtmlGenerator to use DateTime.Now instead of DateTime.UtcNow
- Change ProfileWorker health check timestamps to use DateTime.Now
- Change Program health check endpoint to use DateTime.Now
- Ensures consistent local time usage across the application

ECMJobRunner.WebCron/ProfileWorker/ProfileWorker.cs

@@ -67,7 +67,7 @@ public class ProfileWorker(
                 await work.ExecuteAsync(stoppingToken);
 
                 // Success - update health state
-                _lastSuccessfulRun = DateTime.UtcNow;
+                _lastSuccessfulRun = DateTime.Now;
                 _consecutiveFailures = 0;
                 _lastException = null;
 
@@ -151,7 +151,7 @@ public class ProfileWorker(
             ));
         }
 
-        var timeSinceLastSuccess = DateTime.UtcNow - _lastSuccessfulRun.Value;
+        var timeSinceLastSuccess = DateTime.Now - _lastSuccessfulRun.Value;
         
         // Adaptive multiplier: 3x for fast intervals (<10s), 1.5x for slower intervals
         // This ensures faster problem detection when using longer intervals (e.g., 60s)