fix(python): clean up setuptools usage and drop redundant/unnecessary lock files

[brettcannon]

This leads to more accurate metadata that is declared in a single location:

17c17
< Requires-Python: >=3.8
---
> Requires-Python: >=3.9
29d28
< Dynamic: requires-python

This should close #397 as redundant, but #168 is still pertinent.

[Copilot]

Pull request overview

This PR aims to modernize the Python SDK's build configuration by removing redundant files and consolidating setup configuration into pyproject.toml. The changes improve metadata accuracy (e.g., correctly specifying Python >=3.9 instead of >=3.8) and attempt to simplify the package structure.

Changes:

• Removes setup.py in favor of pyproject.toml declarative configuration
• Removes test-requirements.txt (dependencies now managed via [project.optional-dependencies])
• Removes uv.lock and adds it to .gitignore
• Simplifies setuptools package configuration in pyproject.toml

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
python/setup.py	Removed - redundant with pyproject.toml declarative configuration
python/test-requirements.txt	Removed - test dependencies now in pyproject.toml dev extras
python/uv.lock	Removed - all 579 lines of lock file deleted
python/pyproject.toml	Simplified setuptools configuration from packages.find to explicit packages list
python/.gitignore	Added uv.lock to ignore list