Add railiance01 deployment artifacts and fix container image build

Introduce Dockerfile, entrypoint, and k8s/railiance manifests for the
ArgoCD GitOps pilot (ISSUE-WP-0003). Rename the Gitea PyPI build arg to
GITEA_PYPI_INDEX_URL so pip still resolves dependencies from PyPI.

k8s/railiance/service.yaml

@@ -0,0 +1,19 @@
+# ClusterIP exposing issue-core on 8765 as
+# issue-core.issue-core.svc.cluster.local:8765 — the address activity-core's
+# ISSUE_CORE_URL points at once its k8s runtime port is corrected (8010 -> 8765).
+apiVersion: v1
+kind: Service
+metadata:
+  name: issue-core
+  namespace: issue-core
+  labels:
+    app.kubernetes.io/name: issue-core
+    app.kubernetes.io/part-of: railiance-gitops
+spec:
+  type: ClusterIP
+  selector:
+    app.kubernetes.io/name: issue-core
+  ports:
+    - name: http
+      port: 8765
+      targetPort: http