fix: Docker Compose database initialization

- init-databases.sh: create cameleer3 DB for cameleer3-server, connect
  to $POSTGRES_DB explicitly (avoids 'database cameleer does not exist')
- clickhouse-init.sql: auto-create cameleer database on first start
- docker-compose.yml: fix cameleer3-server datasource to cameleer3 DB,
  add ClickHouse init script volume mount, pass credentials

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker/clickhouse-init.sql

@@ -0,0 +1 @@
+CREATE DATABASE IF NOT EXISTS cameleer;

docker/init-databases.sh

@@ -1,7 +1,9 @@
 #!/bin/bash
 set -e
 
-psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
+psql -v ON_ERROR_STOP=1 --username "$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