[feat]: ultimate normalization script

Going forward, there are likely many times we may want to normalize records. As such, we need a smart script:

**Musts**

- [ ] not bring down production to run script
- it should be a script we can tune to **not** hammer the db, and quietly run in the background
- [ ] easy to define/add transformations
- [ ] fault tolerant
- [ ] keep track of versioning
- must not repeat work - the script should be stopped/started without hesitation, and start off where it left off
- [ ] fearlessly concurrent
- the api will write a `lastUpdated` field to the user record which should allow all ops to be done without losing data

**Niceties**

- [ ] dynamically asks database how loaded it is, and accordingly adjusts ops/rps

**Notes**

Currently, the idea is to add a `schemaVersion` field to the `user` record.

I would prefer to write this in Rust:
1) Ease of distribution
2) Strict typing

That said, this might go against _"easy to define/add transformations"_.

未指定任何文件、测试或入口点。首先明确数据库和 API 接口、提议的 user.schemaVersion 行为，以及转换的定义和版本管理方式。完成标准应包括可恢复、容错且并发安全的执行，并且可以进行限流而不会重复工作或影响生产环境。

由索引模型根据 Issue 内容生成。