Update Python support through 3.14

[jsturtevant]

The Python SDK and Wasm guest packaging should advertise and exercise the same supported CPython minor versions. This updates the declared and tested support range to CPython 3.10 through 3.14, matching the current stable Python payload/tooling without adding prerelease support.

Summary

• Add Python 3.14 to the CI and publish wheel build/test matrices for Linux and Windows.
• Move single-version Python installs used for sandbox/runtime build jobs from 3.12 to 3.14.
• Add explicit Python 3.10-3.14 classifiers across the SDK, native backends, and packaged Wasm guest wheels.
• Align backend maturin build-system requirements with the repo dev toolchain and refresh uv.lock.
• Document the CPython 3.10-3.14 support range in the README.

Notes

The embedded Python runtime in the Wasm payload is already CPython 3.14.0 via componentize-py; this change aligns the SDK metadata and CI/release matrices around that support range.