fix: Replace Ingress with HTTPRoute (Gateway API)

Switch from Ingress to HTTPRoute for Gateway API compatibility.

Changes:
- Remove k8s/ingress.yaml
- Add k8s/httproute.yaml with Gateway API configuration
- Update kustomization.yaml to reference httproute.yaml
- Update README.md references from Ingress to HTTPRoute

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

k8s/kustomization.yaml

@@ -7,7 +7,7 @@ namespace: default
 resources:
   - configmap.yaml
   - statefulset.yaml
-  - ingress.yaml
+  - httproute.yaml
 
 # Uncomment to create secrets from files
 # secretGenerator: