docs: add CLAUDE.md

[almost486]

Summary

• Adds CLAUDE.md to give future Claude Code sessions immediate project context
• Covers project purpose, target platform (Windows PS), setup steps, security tooling, and CI conventions

Test plan

• Verify CLAUDE.md renders correctly on GitHub
• Confirm file is not listed in .gitignore (it shouldn't be — CLAUDE.local.md is ignored, not CLAUDE.md)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Documentation
  • Added comprehensive project documentation covering setup instructions, dependencies, security considerations, and configuration details for developers and contributors.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: b99a7b36-4475-4e72-aef1-bcf468536fde

📥 Commits

Reviewing files that changed from the base of the PR and between 16786c4 and 273f8c4.

📒 Files selected for processing (1)

• CLAUDE.md

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Walkthrough

This PR adds CLAUDE.md, a documentation file that describes the GameVault GamePrep project context, setup requirements including the gitleaks dependency, security scanning practices for pre-commit and CI workflows, guidance on pinning GitHub Actions versions, and CodeRabbit configuration for automated PR reviews.

Changes

Project Documentation

Layer / File(s)	Summary
Project context and setup documentation CLAUDE.md	Introduces project purpose (PowerShell tooling for compressing GOG/Steam game folders into .7z archives), Windows target environment with macOS repo editing, setup steps, required gitleaks dependency, security scanning configuration, and CodeRabbit PR automation settings.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title 'docs: add CLAUDE.md' is fully related to the main change in the changeset, which adds a new CLAUDE.md documentation file.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/add-claude-md

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_{Comment @coderabbitai help to get the list of available commands and usage tips.}