fix: switch Metrics page to Prometheus/node-exporter i915 hwmon source

The Intel GPU device plugin -enable-monitoring flag registers a monitoring
K8s resource type (not a Prometheus endpoint). Real GPU power metrics come
from node-exporter's hwmon collector which scrapes the i915 kernel driver.

- Rewrite src/api/metrics.ts: query kube-prometheus-stack Prometheus for
  node_hwmon_energy_joule_total (rate → watts), node_hwmon_power_max_watt
  (TDP), joined with node_hwmon_chip_names{chip_name="i915"} to identify
  GPU chips. Instance → node name resolved via node_uname_info.

- Rewrite src/components/MetricsPage.tsx: shows per-chip current power (W)
  with bar vs TDP, total fleet power summary, last-fetched timestamp.
  Auto-discovers Prometheus service in monitoring namespace.

- Update artifacthub-pkg.yml checksum for repackaged v0.2.0 tarball.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

artifacthub-pkg.yml

@@ -46,7 +46,7 @@ links:
 
 changes:
   - kind: added
-    description: "Metrics page: real-time engine utilization, boost frequency, VRAM usage, and energy from Intel GPU device plugin Prometheus endpoint (port 9090)"
+    description: "Metrics page: real-time GPU power draw (W) and TDP via node-exporter i915 hwmon metrics in kube-prometheus-stack"
   - kind: changed
     description: "Sidebar label changed to intel-gpu"
   - kind: removed
@@ -70,6 +70,6 @@ changes:
 
 annotations:
   headlamp/plugin/archive-url: "https://github.com/privilegedescalation/headlamp-intel-gpu-plugin/releases/download/v0.2.0/headlamp-intel-gpu-plugin-0.2.0.tar.gz"
-  headlamp/plugin/archive-checksum: "sha256:404be582bd13c167f61785028eb6eb91dd621106cbe76038f2c071a576a1a442"
+  headlamp/plugin/archive-checksum: "sha256:cbcd20916d72e91ccc36143c74680fbeb2f045e1cbe6d1cc0d844b198e2a1ea5"
   headlamp/plugin/version-compat: ">=0.20.0"
   headlamp/plugin/distro-compat: "in-cluster,web,app"