Add __for_llm__ auto-detection to llmtool

[erikgaas]

Enhances @llmtool to auto-detect __for_llm__ classmethod on the first param's class.

Adds helper functions:

• params(f, exclude) - get parameter annotations
• extract_args(names, a, kw) - extract args from positional/kwargs
• call_via(via, method_name, a, kw, via_keys) - create object via factory and call method
• merge_hints(via, f) - combine type hints from two functions

Usage:

class Page:
    @classmethod
    def __for_llm__(cls, tab_id: int) -> Page: ...

@llmtool
def read(self:Page) -> str: ...

One decorator that patches the method AND creates a tool version.

[erikgaas]

I was thinking that this should be in tools.py, but im guessing there is an issue with that so it was put here so it was loaded before any other code.

[jph00]

Yeah this has gotten big enough now that it should be removed from imports and put in a proper nb, with explanations/examples/etc. Maybe a new section in xtras?