fix: resolve duplicate statSync calls, typo, and update platform support

[eren-karakus0]

Summary

• Performance: Optimize buildEntries() in file-tree-navigator.ts by caching the fs.statSync() result instead of calling it twice per directory entry. This reduces unnecessary syscalls during file tree navigation.
• Typo: Fix Rretrieve → Retrieve in download.ts comment.
• Docs: Update README system requirements to include Windows (WSL), matching the win32 entry already listed in package.json.

Changes

File	Change
src/guide/util/file-tree-navigator.ts	Cache statSync result to avoid duplicate call per entry
src/guide/download.ts	Fix typo in comment
README.md	Add Windows (WSL) to supported platforms

Test plan

• Verified buildEntries() produces identical output with single statSync call
• Confirmed package.json already lists win32 in os field
• No behavioral changes — only performance optimization, typo fix, and docs update

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Note

Low Risk
Documentation and minor CLI UX/performance changes with no behavioral changes to network/storage operations.

Overview
Updates the quickstart docs to explicitly list Windows (WSL) as a supported platform.

Fixes a small typo in the download guide comment, and slightly optimizes buildEntries() in file-tree-navigator.ts by caching the fs.statSync() directory check per entry to avoid duplicate filesystem calls while building the selection list.

^{Written by Cursor Bugbot for commit a6b84fe. This will update automatically on new commits. Configure here.}