Support Python 3.14

[adamtheturtle]

Add Python 3.14 to the test matrix and classifiers.

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Note

Add Python 3.14 support

• Adds Python 3.14 to GitHub Actions test matrix (Ubuntu, Windows)
• Updates pyproject.toml classifiers and tool.pyproject-fmt.max_supported_python to 3.14
• Refreshes dev dependency pins and lockfile (e.g., doccmd, pydocstringformatter, pyrefly)

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