Add autocomplete for operator

To avoid mistakes it would be great to have operator autocomplete in types.

We could either just use a union type and then allow also for any string to account for custom operators, or we could be strict and pair each operator with its corresponding value (e.g. `lessThan` needs a `value: number`, and we could document them so users know how to extend that with their custom types.

If there is interest in this I'd be happy to contribute the PR.

Thanks in advance.

从 issue 提案开始，检查 repository 中现有的类型定义和运算符处理方式。将提议的基于 union 的自动补全与成对的运算符/值类型进行比较，包括应如何扩展自定义运算符。完成的标准是：所选设计提供运算符自动补全，并清晰地记录自定义类型。

由索引模型根据 Issue 内容生成。