Build Tempo container from source (2.10.3) (#323)

## Summary
- Add `containers/tempo/Dockerfile` — two-stage Go build from forge mirror, modeled on loki
- Switch kustomization from upstream `grafana/tempo` to `registry.ops.eblu.me/blumeops/tempo`
- Bump Tempo 2.10.1 → 2.10.3

## Test plan
- [ ] Kick off container build via `mise run container-build-and-release tempo`
- [ ] Update kustomization `newTag` with built image tag
- [ ] Deploy from branch: `argocd app set tempo --revision local-tempo-container && argocd app sync tempo`
- [ ] Verify Tempo health: `curl tempo.ops.eblu.me/ready`
- [ ] Verify traces flowing in Grafana Tempo datasource

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

Reviewed-on: #323

service-versions.yaml

@@ -65,9 +65,10 @@ services:
 
   - name: tempo
     type: argocd
-    last-reviewed: 2026-03-05
-    current-version: "2.10.1"
+    last-reviewed: 2026-04-02
+    current-version: "2.10.3"
     upstream-source: https://github.com/grafana/tempo/releases
+    notes: Home-built container from forge mirror
 
   - name: alloy-tracing-ringtail
     type: argocd