Fix PyInstaller version data collision

[yxshee]

Summary

• Rename the packaged arcade/VERSION data file to arcade/_VERSION and update all readers, package metadata, and contributor documentation.
• Correct the PyInstaller hook's data destination to the arcade directory; PyInstaller interprets the second tuple item as a destination directory, not a file path.
• Add regression coverage for case-insensitive package-name collisions and the hook's final bundled _VERSION path.

Root cause and impact

The version data file case-folded to the same name as the arcade.version module. The hook also used ./arcade/VERSION as a filename-shaped destination, although PyInstaller treats that value as a directory. Together with collect_all("arcade"), this caused a file/directory collision during the Windows COLLECT phase.

The public arcade.VERSION and arcade.__version__ APIs are unchanged.

Fixes #2837

Validation

• pytest tests/unit/test_version.py tests/unit/test_pyinstaller_hook.py -q — 32 passed
• Ruff formatting, import sorting, and lint checks on changed Python files — passed
• mypy and repository-pinned pyright on changed source files — passed
• uv build — wheel and sdist built; both contain arcade/_VERSION and no arcade/VERSION
• PyInstaller 6.21 smoke build with --collect-all arcade — completed; frozen executable printed 4.0.0.dev5 and contained _internal/arcade/_VERSION

Disclosure: this contribution was prepared with AI assistance. I reviewed the final diff and ran every check listed above.

[Copilot]

Pull request overview

This PR resolves a Windows PyInstaller collect_all("arcade") collision by renaming the packaged version data file from arcade/VERSION to arcade/_VERSION, updating readers and packaging inputs, and adding regression tests to prevent future case-insensitive path conflicts.

Changes:

• Renamed the packaged version data file to arcade/_VERSION and updated code paths that read it.
• Corrected the PyInstaller hook data destination to target the arcade directory (as required by PyInstaller’s (source, dest_dir) semantics).
• Added regression tests covering case-folded collisions and the bundled _VERSION destination path.

Reviewed changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
webplayground/server.py	Updates local web playground version-file read path to _VERSION.
tests/unit/test_version.py	Adds tests to ensure _VERSION is loaded and data/module names don’t collide when case-folded.
tests/unit/test_pyinstaller_hook.py	Adds regression test asserting _VERSION is bundled to arcade/_VERSION.
RELEASE_CHECKLIST.md	Updates release instructions to point to arcade/_VERSION.
MANIFEST.in	Updates sdist inclusion rule from VERSION to _VERSION.
doc/conf.py	Updates commented-out version read path to _VERSION.
CHANGELOG.md	Documents the PyInstaller collision fix.
arcade/version.py	Switches default version file path and updates docstrings to _VERSION.
arcade/_VERSION	Adds the new version data file.
arcade/__pyinstaller/hook-arcade.py	Updates hook to collect _VERSION and fixes the destination directory.

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