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/initdb/10-peo.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# SPDX-FileCopyrightText: 2026 Bart Broere
+# SPDX-License-Identifier: GPL-3.0-or-later
+# Prepares a freshly initialised cluster for peo.
+set -euo pipefail
+
+# The bridge connects over 127.0.0.1 with the credentials users log in with, so
+# loopback TCP connections must check passwords. The postgres image trusts them
+# by default; Unix-socket connections (psql inside the container) stay trusted.
+sed -i -E 's/^(host[[:space:]]+[^[:space:]]+[[:space:]]+[^[:space:]]+[[:space:]]+(127\.0\.0\.1\/32|::1\/128)[[:space:]]+)trust/\1scram-sha-256/' \
+    "$PGDATA/pg_hba.conf"
+
+# Create the default AGE graph that neo4j-browser opens on first connect.
+psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "${POSTGRES_DB:-$POSTGRES_USER}" \
+    -v graph="${PEO_DEFAULT_GRAPH:-neo4j}" <<'EOSQL'
+LOAD 'age';
+SET search_path = ag_catalog, "$user", public;
+SELECT ag_catalog.create_graph(:'graph')
+WHERE NOT EXISTS (SELECT 1 FROM ag_catalog.ag_graph WHERE name = :'graph');
+EOSQL