Rename Borgmatic dashboard to Borg Backups, add duration graph

Rename dashboard title since borgmatic is just the execution layer.
Add Backup Duration Over Time panel next to New Data Per Backup.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

argocd/manifests/grafana-config/dashboards/configmap-borgmatic.yaml

@@ -743,7 +743,7 @@ data:
             },
             "overrides": []
           },
-          "gridPos": { "h": 8, "w": 24, "x": 0, "y": 16 },
+          "gridPos": { "h": 8, "w": 12, "x": 0, "y": 16 },
           "id": 13,
           "options": {
             "legend": {
@@ -769,11 +769,94 @@ data:
           "title": "New Data Per Backup",
           "description": "How much new (deduplicated) data each backup added to the repository",
           "type": "timeseries"
+        },
+        {
+          "datasource": {
+            "type": "prometheus",
+            "uid": "prometheus"
+          },
+          "fieldConfig": {
+            "defaults": {
+              "color": {
+                "fixedColor": "yellow",
+                "mode": "fixed"
+              },
+              "custom": {
+                "axisBorderShow": false,
+                "axisCenteredZero": false,
+                "axisColorMode": "text",
+                "axisLabel": "",
+                "axisPlacement": "auto",
+                "barAlignment": 0,
+                "drawStyle": "bars",
+                "fillOpacity": 80,
+                "gradientMode": "none",
+                "hideFrom": {
+                  "legend": false,
+                  "tooltip": false,
+                  "viz": false
+                },
+                "insertNulls": false,
+                "lineInterpolation": "linear",
+                "lineWidth": 1,
+                "pointSize": 5,
+                "scaleDistribution": {
+                  "type": "linear"
+                },
+                "showPoints": "never",
+                "spanNulls": false,
+                "stacking": {
+                  "group": "A",
+                  "mode": "none"
+                },
+                "thresholdsStyle": {
+                  "mode": "off"
+                }
+              },
+              "mappings": [],
+              "thresholds": {
+                "mode": "absolute",
+                "steps": [
+                  { "color": "green", "value": null },
+                  { "color": "yellow", "value": 60 },
+                  { "color": "red", "value": 300 }
+                ]
+              },
+              "unit": "s"
+            },
+            "overrides": []
+          },
+          "gridPos": { "h": 8, "w": 12, "x": 12, "y": 16 },
+          "id": 15,
+          "options": {
+            "legend": {
+              "calcs": ["mean", "max", "lastNotNull"],
+              "displayMode": "table",
+              "placement": "right",
+              "showLegend": true
+            },
+            "tooltip": {
+              "mode": "single",
+              "sort": "none"
+            }
+          },
+          "pluginVersion": "10.0.0",
+          "targets": [
+            {
+              "datasource": { "type": "prometheus", "uid": "prometheus" },
+              "expr": "borgmatic_last_archive_duration_seconds",
+              "legendFormat": "Backup Duration",
+              "refId": "A"
+            }
+          ],
+          "title": "Backup Duration Over Time",
+          "description": "How long each backup took to complete",
+          "type": "timeseries"
         }
       ],
       "refresh": "5m",
       "schemaVersion": 38,
-      "tags": ["borgmatic", "backup", "borg"],
+      "tags": ["borg", "backup"],
       "templating": {
         "list": []
       },
@@ -783,7 +866,7 @@ data:
       },
       "timepicker": {},
       "timezone": "browser",
-      "title": "Borgmatic Backups",
+      "title": "Borg Backups",
       "uid": "borgmatic",
       "version": 1,
       "weekStart": ""