feat(install): add macOS permission checker for hotkeys

[basnijholt]

Summary

• Add agent-cli install-hotkeys --check command to diagnose permission issues on macOS
• New Python module agent_cli/install/permissions.py with comprehensive checks
• Auto-runs permission check after install-hotkeys on macOS
• Updated documentation with detailed permission troubleshooting guide

What it checks

Check	Description
macOS Version	Compatibility verification
skhd	Installation and service status
terminal-notifier	Installation status
agent-cli	Installation location
skhd Config	Hotkey configuration
Accessibility	Permission for keyboard shortcuts
Microphone	Permission for transcription
Notifications	Delivery test and settings
Local Services	AI service connectivity

Usage

# Check permissions only
agent-cli install-hotkeys --check

# Install hotkeys (auto-runs check after on macOS)
agent-cli install-hotkeys

Example output

Agent-CLI Permission Checker
Diagnosing hotkey setup issues...

╭─────────────────────╮
│ Installation Checks │
╰─────────────────────╯
  ✓ macOS Version: macOS 15.7.2 (supported)
  ✓ skhd Installation: Found at /opt/homebrew/bin/skhd
  ✓ skhd Service: Running
  ...

╭───────────────────╮
│ Permission Checks │
╰───────────────────╯
  ✓ Accessibility: skhd is running (likely has permission)
  ✓ Microphone: Access authorized
  ✓ Notifications: Test notification sent
  ...

✓ All checks passed!

Test plan

• Run agent-cli install-hotkeys --check on macOS
• Verify all checks pass on properly configured system
• Verify lint passes (ruff check)
• Test on fresh macOS install to verify fix suggestions work