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.

Dockerfile

@@ -0,0 +1,33 @@
+# issue-core REST ingestion service image.
+#
+# Installs the published issue-core[api] package from the Coulomb Gitea PyPI
+# index (no sibling-checkout build context) and runs the FastAPI ingestion
+# server on :8765. Built and pushed to gitea.coulomb.social/coulomb/issue-core.
+FROM python:3.12-slim AS runtime
+
+ARG ISSUE_CORE_VERSION=">=0.2,<0.3"
+# Do not name this PIP_INDEX_URL — Docker exposes ARGs as env vars during RUN,
+# and pip treats PIP_INDEX_URL as the sole primary index (excluding PyPI).
+ARG GITEA_PYPI_INDEX_URL=https://gitea.coulomb.social/api/packages/coulomb/pypi/simple/
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    HOME=/home/app
+
+# Non-root runtime user; HOME drives issue-core's config dir
+# (~/.config/issue-tracker/backends.json).
+RUN useradd --create-home --home-dir /home/app --uid 10001 app
+
+RUN pip install --no-cache-dir \
+        --index-url https://pypi.org/simple \
+        --extra-index-url "${GITEA_PYPI_INDEX_URL}" \
+        "issue-core[api]${ISSUE_CORE_VERSION}"
+
+COPY docker-entrypoint.sh /usr/local/bin/docker-entrypoint.sh
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
+
+USER app
+EXPOSE 8765
+
+# Entrypoint renders backends.json from env, then execs the server.
+ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]