minor: add function overload in python api

[zhourrr]

No description provided.

[greptile-apps]

Greptile Summary

Added Python @overload decorators to four collection methods (insert, upsert, update, delete) to provide better type hints for IDEs and static type checkers. When a single document or ID is passed, the return type is correctly inferred as Status; when a list is passed, the return type is list[Status]. This improves developer experience with better autocomplete and type safety without changing any runtime behavior.

Confidence Score: 5/5

• This PR is safe to merge with no risk
• The changes are purely additive type annotations using Python's @overload decorator, which only affects static type checking and IDE autocomplete. No runtime behavior is modified, and the overload signatures correctly match the existing implementation logic.
• No files require special attention

Important Files Changed

Filename	Overview
python/zvec/model/collection.py	Added @overload decorators for type-safe method signatures on insert, upsert, update, and delete methods

_{Last reviewed commit: 9d58c4a}

[Cuiyus]

@greptile