feat(deploy): Starter PostgreSQL backup and safe new-database restore

用户直接交办 CP-06：在不等待云配置的前提下完成 Starter PostgreSQL 备份/恢复能力及真实隔离恢复验收。通过专属 PostgreSQL 16 容器的 pg_dump/pg_restore，创建私有dump+checksum manifest，仅恢复到新数据库，不覆盖已有实例；明确生产RDS恢复与OSS上传不在此次已验收范围。关联CP-05初始化 #3426，独立交付PR。

Start with the related CP-05 initialization issue #3426 and locate the Starter deployment entry point and dedicated PostgreSQL 16 container configuration. Trace the pg_dump/pg_restore flow and checksum manifest handling; done means restoring only into a new database without overwriting existing instances, while production RDS restore and OSS upload remain out of scope.

Written by the indexing model from the issue text.