Add peo4c: neo4j-browser on PostgreSQL + Apache AGE

A single container image with:
- neo4j-browser built from source and served on :7474
- PostgreSQL with Apache AGE (based on apache/age)
- a Python bridge speaking Bolt 4.4/5.0-5.4 over TCP and WebSocket on
  :7687 that runs Cypher through AGE's cypher() function, emulates the
  Neo4j procedures neo4j-browser relies on, and maps databases to AGE
  graphs

Includes workarounds for AGE limitations (parameters are inlined as
literals, `id(x) IN [...]` and the browser's expand-node query are
rewritten) and an end-to-end smoke test using the Neo4j Python driver.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Dockerfile

@@ -0,0 +1,46 @@
+# peo4c: neo4j-browser on top of PostgreSQL + Apache AGE.
+#
+# Stage 1 builds the neo4j-browser static frontend from source.
+# Stage 2 is the Apache AGE image (PostgreSQL with the AGE extension) plus the
+# peo4c bridge, which speaks the Bolt protocol to the browser and translates
+# Cypher into AGE `cypher()` calls.
+
+ARG AGE_IMAGE=docker.io/apache/age:release_PG18_1.8.0
+
+FROM docker.io/library/node:16.20.2-bullseye AS browser
+
+ARG NEO4J_BROWSER_REPO=https://github.com/neo4j/neo4j-browser.git
+ARG NEO4J_BROWSER_REF=3928c10fd6f148fd615b391d27d3fd6ce43a9044
+
+WORKDIR /src
+RUN git init -q . \
+    && git remote add origin "$NEO4J_BROWSER_REPO" \
+    && git fetch -q --depth 1 origin "$NEO4J_BROWSER_REF" \
+    && git checkout -q FETCH_HEAD
+RUN yarn install --frozen-lockfile --network-timeout 600000
+RUN yarn build && test -f dist/index.html
+
+
+FROM ${AGE_IMAGE}
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends python3 python3-psycopg \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=browser /src/dist /opt/peo4c/browser
+COPY bridge /opt/peo4c/bridge
+COPY docker/initdb/ /docker-entrypoint-initdb.d/
+COPY docker/peo4c-entrypoint.sh /usr/local/bin/peo4c-entrypoint.sh
+
+ENV PEO4C_DEFAULT_GRAPH=neo4j \
+    PEO4C_BROWSER_DIR=/opt/peo4c/browser \
+    PEO4C_HTTP_PORT=7474 \
+    PEO4C_BOLT_PORT=7687 \
+    PEO4C_PG_HOST=127.0.0.1 \
+    PEO4C_PG_PORT=5432
+
+# 7474: neo4j-browser (HTTP), 7687: Bolt, 5432: PostgreSQL
+EXPOSE 7474 7687 5432
+
+ENTRYPOINT ["/usr/local/bin/peo4c-entrypoint.sh"]
+CMD ["postgres", "-c", "shared_preload_libraries=age"]