Add macOS cleanup commands for caches and logs

[KevinDeBenedetti]

Goal

Provide a cleanup.sh script (or make clean target) that frees disk space
on macOS by clearing system and user-level caches, logs, and temp files.

Acceptance criteria

• Script lists categories with estimated size before deleting
• Each category is opt-in (flags or interactive prompts)
• Homebrew cache cleanup included
• Script added to os/macos/ and referenced in Makefile
• Documentation updated in docs/setup/

[KevinDeBenedetti]

🤖 Synced from TODO.yml

Type	feat
Status	backlog
Priority	medium