Consolidate Python dependency updates

[jsturtevant]

Summary

• raise agent-framework-devui to >=1.0.0b260730 and agent-framework-github-copilot to >=1.0.1
• update cryptography to 50.0.0 and Ruff to >=0.16.2 in the coherent uv lockfile
• apply Ruff 0.16 Markdown formatting to the Python SDK README instead of excluding Markdown

Validation

• uv lock --check
• just fmt / just fmt-check (Rust and Python passed; local aggregate reached an unavailable .NET SDK)
• just build (all non-.NET stages and the .NET FFI build passed; local aggregate reached an unavailable .NET SDK)
• just examples (WASM, JS, and Python examples passed; local aggregate reached an unavailable .NET SDK)
• updated Agent Framework and DevUI API smoke test

Supersedes #170
Supersedes #172
Supersedes #173
Supersedes #175

[Copilot]

Pull request overview

This PR consolidates Python dependency updates and aligns the repository’s Python toolchain and documentation formatting with newer package/tool versions.

Changes:

• Updated Agent Framework-related Python dependencies (DevUI and GitHub Copilot integrations) and refreshed the uv.lock resolution accordingly.
• Bumped security- and tooling-relevant dependencies in uv.lock, including cryptography==50.0.0 and a newer resolved Ruff version while keeping the requirement at >=0.16.2.
• Applied Ruff 0.16-era Markdown/Python formatting to the Python SDK README code snippet.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
uv.lock	Updates resolved Python dependency set (Agent Framework packages, cryptography 50.0.0, Ruff resolution, and transitive additions like msgspec).
src/sdk/python/core/README.md	Reformats the Quick Start snippet to match current Ruff formatting behavior.
pyproject.toml	Raises minimum Ruff and Agent Framework-related dependency requirements.

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