fix: Updated to Python 3.14 and Pydantic V2 (kinda)

[Stoupy51]

Fixes #16

Half-Vibe-codded until it worked fine because I'm not familiar with Pydantic.
If Claude made some things strange, this PR is editable by maintainers, so you can fix it.

Here is a screenshot of the output when calling weld, looks fine and merged fine.

Example of function tag

[rx-dev]

btw, i will work on this in the next couple of days 🤞🏽.
i may not use ur exact commits but i'll attribute one w/ co-author for the work u put in.

i plan to combine the move to pydantic v2 with a bit of a change on how the model is saved in the project.

[Stoupy51]

You can always dev on this PR branch and finally squash merge to maintain a clean history.

[rx-dev]

maybe but i'm doing a major refactor of weld that'll cause conflicts that will be hard to fix

[Stoupy51]

Okay yeah, better to start from where you were I guess