Add [Y/n/a] prompt support where 'a' = auto-yes to all remaining prompts.

Features:
- New _prompt_with_auto_all() helper function
- All install prompts now support [Y/n/a] options
- Selecting 'a' enables auto-yes for all future prompts
- Works with Chocolatey, Node.js, PHP, and tool installation prompts

User Experience:
- First prompt: 'Install all 8 missing tools? [Y/n/a]:'
- Select 'a' → all subsequent prompts auto-answered yes
- No more repetitive prompting during installation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>