Refactor examples to use PEP 723 inline script metadata

[maxisbey]

Summary

Simplify the examples directory by using PEP 723 inline script metadata instead of individual pyproject.toml files per example.

Motivation

• Current examples are verbose - each needs its own pyproject.toml, directory structure, and __main__.py
• This adds friction for users trying to understand or copy examples
• PEP 723 (supported by uv run) allows dependencies to be declared inline in a single script file

Goal

Examples that are single self-contained .py files runnable with uv run example.py, making them easier to read, copy, and adapt.

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