feat: Add CI/CD pipeline with Docker build and K8s deployment

Add Dockerfile (multi-stage, python:3.11-slim + uv), K8s manifests
(Deployment + Service), and extend CI workflow with build-push-deploy
stages targeting Gitea registry and K3s.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

k8s/service.yaml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: haproxy-mcp
+  namespace: default
+  labels:
+    app: haproxy-mcp
+spec:
+  type: ClusterIP
+  selector:
+    app: haproxy-mcp
+  ports:
+    - port: 8000
+      targetPort: 8000
+      protocol: TCP
+      name: mcp