feat: create cameleer-postgres image with init script baked in

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker/cameleer-postgres/init-databases.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+set -e
+
+psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-EOSQL
+    CREATE DATABASE logto;
+    CREATE DATABASE cameleer3;
+    GRANT ALL PRIVILEGES ON DATABASE logto TO $POSTGRES_USER;
+    GRANT ALL PRIVILEGES ON DATABASE cameleer3 TO $POSTGRES_USER;
+EOSQL