claude-notify: add PermissionRequest hook alongside Stop hook

[congmnguyen]

Summary

• Add PermissionRequest hook back alongside the existing Stop hook
• Both hooks call ~/bin/claude-notify with different messages ("Done!" vs "Needs your input!")
• Both already skip notification when Windows Terminal is the active window via the foreground-window check in the script
• Update docs to reflect that both hooks are active

Test plan

• Restart Claude Code after settings change
• Finish a task while in another window — "Done!" balloon should appear
• Trigger a permission prompt while in another window — "Needs your input!" balloon should appear
• Both should be silent when Windows Terminal is the active window