Rename Node Exporter dashboard to macOS (#22)

## Summary
- Renamed dashboard from "Node Exporter - macOS" to just "macOS" since it now uses Alloy
- Updated filename, title, uid, and tags to reflect the change

## Deployment and Testing
- [ ] Deploy with `mise run provision-indri -- --tags grafana`
- [ ] Verify dashboard accessible at https://grafana.tail8d86e.ts.net

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: https://forge.tail8d86e.ts.net/eblume/blumeops/pulls/22

ansible/roles/grafana/files/dashboards/macos.json

@@ -1248,7 +1248,7 @@
   ],
   "refresh": "30s",
   "schemaVersion": 38,
-  "tags": ["node-exporter", "macos", "darwin"],
+  "tags": ["macos", "darwin"],
   "templating": {
     "list": [
       {
@@ -1319,8 +1319,8 @@
   },
   "timepicker": {},
   "timezone": "browser",
-  "title": "Node Exporter - macOS",
-  "uid": "node-exporter-macos",
+  "title": "macOS",
+  "uid": "macos",
   "version": 1,
   "weekStart": ""
 }