chore(release): prepare project for publishing

[jradcliff]

• Packaging & Metadata:

  • Add [project.urls] for PyPI sidebar links (Homepage, Docs, Repo, Issues).
  • Update license to standard SPDX expression "Apache-2.0" (PEP 639).
  • Clean up classifiers and add "Operating System :: OS Independent".
  • Remove <3.14 upper bound on requires-python.
  • Add PEP 561 py.typed marker and package-data configuration.

• Documentation:

  • Fix RST link syntax for CONTRIBUTING.md in README.rst.
  • Fix RST subheadings and code literal backticks under "Run samples".
  • Add bash syntax highlighting to installation code block.
  • Add Lindsey Volta to authors list.

• Tooling & Python 3.14:

  • Add Python 3.14 to noxfile test matrix and pyproject classifiers.
  • Update coverage test dependency to >=7.0.0.
  • Configure [tool.black] in pyproject.toml and simplify nox format session.
  • Remove set -x from release.sh.

Change-Id: I335c981a8a8b44d80662dd7a080ed45a5852b8f6