fix: silence aiohttp.access log and strip plugin prefix in alerts UI

- main: disable aiohttp.access propagation unless --debug is active
- alerts.html: strip plugin-name prefix from metric_path display
  (nagios_runner.check_disk_root_status_code → check_disk_root_status_code)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/server/templates/alerts.html

@@ -439,7 +439,7 @@
                 <span class="alert-level ${level}">${alert.level}</span>
                 <a class="alert-hostname" href="/plugins#${alert.hostname}">${alert.hostname}</a>
               </div>
-              <div class="alert-metric">${alert.metric_path}</div>
+              <div class="alert-metric">${alert.metric_path.includes('.') ? alert.metric_path.slice(alert.metric_path.indexOf('.') + 1) : alert.metric_path}</div>
               <div class="alert-details">
                 <span>${valueText}</span>
                 <span class="alert-duration">Active for ${duration}</span>