chore: add .gitattributes to normalize line endings

[oco777]

Motivation

• Enforce LF (eol=lf) as the canonical line ending and ensure Unity-related files and common docs/configs are handled correctly by Git.

Description

• Add repository-root .gitattributes with * text=auto eol=lf, explicit text eol=lf rules for Unity/C#/UI Toolkit files (*.cs, *.uxml, *.uss, *.shader, *.compute, *.meta), rules for docs/config (*.md, *.txt, *.json, *.yml, *.yaml), and binary entries for image, audio, font, model and scene extensions (e.g. *.png, *.wav, *.ttf, *.fbx, *.unity).

Testing

• No automated tests were run for this change.

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Codex Task

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Treat Unity scene files as text, not binary

Marking *.unity as binary prevents Git from doing line-based diffs and merges on scene files, which are YAML text. This makes resolving concurrent edits to scenes much harder (Git won’t attempt textual merges and most tooling will treat the file as opaque), so collaborating on scene changes becomes painful and conflicts are more likely to require manual rework. Consider keeping *.unity as text eol=lf like other Unity YAML assets.

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