Format drifted files to satisfy the treefmt flake-check gate

Pure formatting (nixfmt/prettier/yamlfmt); no behavior change. These
files predate the current treefmt config and were failing nix flake
check; reformatting them makes the gate green again.

modules/monitoring/dashboards/dns.json

@@ -224,7 +224,10 @@
       "options": { "showHeader": true },
       "fieldConfig": {
         "defaults": {
-          "custom": { "align": "auto", "cellOptions": { "type": "color-background" } },
+          "custom": {
+            "align": "auto",
+            "cellOptions": { "type": "color-background" }
+          },
           "thresholds": {
             "mode": "absolute",
             "steps": [
@@ -245,15 +248,21 @@
         "overrides": [
           {
             "matcher": { "id": "byName", "options": "zone" },
-            "properties": [{ "id": "custom.cellOptions", "value": { "type": "auto" } }]
+            "properties": [
+              { "id": "custom.cellOptions", "value": { "type": "auto" } }
+            ]
           },
           {
             "matcher": { "id": "byName", "options": "query" },
-            "properties": [{ "id": "custom.cellOptions", "value": { "type": "auto" } }]
+            "properties": [
+              { "id": "custom.cellOptions", "value": { "type": "auto" } }
+            ]
           },
           {
             "matcher": { "id": "byName", "options": "instance" },
-            "properties": [{ "id": "custom.cellOptions", "value": { "type": "auto" } }]
+            "properties": [
+              { "id": "custom.cellOptions", "value": { "type": "auto" } }
+            ]
           }
         ]
       },
@@ -283,7 +292,10 @@
       "id": 22,
       "datasource": { "type": "prometheus", "uid": "victoriametrics" },
       "gridPos": { "h": 8, "w": 12, "x": 12, "y": 43 },
-      "fieldConfig": { "defaults": { "unit": "short", "min": 0, "max": 1 }, "overrides": [] },
+      "fieldConfig": {
+        "defaults": { "unit": "short", "min": 0, "max": 1 },
+        "overrides": []
+      },
       "targets": [
         {
           "refId": "A",