ops: glance borg-backup-widget via prometheus + synthwave/matrix presets

- glance zusaetzlich in monitoring_net (nur lesende Prometheus-Query, kein neuer Listener)
- Borg-Widget: Backup-Alter aus homelab_borg_last_completed_timestamp_seconds, Status aus homelab_borg_last_success
- Theme-Presets synthwave und matrix

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ops/glance/config/glance.yml

@@ -34,6 +34,19 @@ theme:
       primary-color: 212 100 35
       positive-color: 140 70 30
       negative-color: 0 70 45
+    synthwave:
+      background-color: 265 35 10
+      primary-color: 320 100 65
+      positive-color: 175 100 50
+      negative-color: 0 100 65
+      contrast-multiplier: 1.3
+    matrix:
+      background-color: 130 25 6
+      primary-color: 130 100 55
+      positive-color: 130 100 45
+      negative-color: 35 100 55
+      contrast-multiplier: 1.25
+      text-saturation-multiplier: 1.2
 
 pages:
   $include: pages.yml