Use Starlette, uvicorn and websockets; rename Docker files to container ones

Serve neo4j-browser with Starlette and uvicorn (the optional browser extra)
instead of a hand-written HTTP server, and handle Bolt over WebSocket with the
websockets library's Sans-I/O protocol. Rename Dockerfile, .dockerignore and
docker/ to Containerfile, .containerignore and container/.

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

container/peo-entrypoint.sh

@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: 2026 Bart Broere
+# SPDX-License-Identifier: GPL-3.0-or-later
+# Runs PostgreSQL (through the stock postgres entrypoint), the peo bridge and
+# pgAdmin side by side. The container stops when PostgreSQL or the bridge exits;
+# pgAdmin is optional and its failure does not take the others down.
+set -euo pipefail
+
+if [ "${1:-}" != "postgres" ]; then
+    exec docker-entrypoint.sh "$@"
+fi
+
+export PEO_PG_DATABASE="${PEO_PG_DATABASE:-${POSTGRES_DB:-${POSTGRES_USER:-postgres}}}"
+
+start_pgadmin() {
+    local app=/opt/pgadmin/app
+    local email="${PGADMIN_DEFAULT_EMAIL:-admin@example.com}"
+
+    if [ ! -f /var/lib/pgadmin/pgadmin4.db ]; then
+        # First start: create the login user and register the bundled PostgreSQL.
+        cat > /var/lib/pgadmin/servers.json <<EOF
+{"Servers": {"1": {"Name": "peo", "Group": "Servers", "Host": "127.0.0.1", "Port": 5432,
+ "MaintenanceDB": "${PEO_PG_DATABASE}", "Username": "${POSTGRES_USER:-postgres}", "SSLMode": "prefer"}}}
+EOF
+        chown postgres:postgres /var/lib/pgadmin/servers.json
+        PGADMIN_SETUP_EMAIL="$email" \
+            PGADMIN_SETUP_PASSWORD="${PGADMIN_DEFAULT_PASSWORD:-${POSTGRES_PASSWORD:-}}" \
+            gosu postgres /opt/pgadmin/bin/python "$app/setup.py" setup-db \
+            && gosu postgres /opt/pgadmin/bin/python "$app/setup.py" load-servers \
+                /var/lib/pgadmin/servers.json --user "$email" \
+            || { rm -f /var/lib/pgadmin/pgadmin4.db; return 1; }
+    fi
+
+    gosu postgres /opt/pgadmin/bin/gunicorn --bind "0.0.0.0:${PEO_PGADMIN_PORT}" \
+        --workers 1 --threads 25 --timeout 0 --chdir "$app" --log-level warning pgAdmin4:app &
+    pgadmin_pid=$!
+    echo "peo: pgAdmin on http://localhost:${PEO_PGADMIN_PORT}/ (login: $email)"
+}
+
+docker-entrypoint.sh "$@" &
+pg_pid=$!
+
+gosu postgres /opt/peo/venv/bin/peo &
+bridge_pid=$!
+
+pgadmin_pid=
+if [ "${PEO_PGADMIN}" = "true" ]; then
+    start_pgadmin || echo "peo: WARNING: pgAdmin setup failed, continuing without it" >&2
+fi
+
+shutdown() {
+    for pid in "$bridge_pid" $pgadmin_pid "$pg_pid"; do
+        kill -TERM "$pid" 2>/dev/null || true
+    done
+}
+trap shutdown TERM INT
+
+# Wait until PostgreSQL or the bridge exits, then stop everything.
+set +e
+wait -n "$pg_pid" "$bridge_pid"
+status=$?
+shutdown
+wait 2>/dev/null
+exit "$status"