feat(peon-ping): ✨ play host sounds through the relay, no packs

[baxyz]

Summary

• The container no longer installs peon-ping or any sound pack. Hooks ask the peon-ping relay on the host to play a sound category (/play?category=); the host picks the pack and volume, so there is nothing to mirror or configure and no initializeCommand.
• One script, /usr/local/bin/peon-ping, with three subcommands: hook (called by the agents), register (postCreateCommand, adds the hooks for Claude Code, Cursor and Codex idempotently) and check (postStartCommand, makes host.docker.internal resolve on native Linux Docker and tells the user to start the relay on the host if it is down).
• Removes the packs, packsLang, volume, noRc and ideSetup options and the peon-ping-copilot-setup helper. Breaking, version set to 1.3.2.
• Starting the relay on the host stays a manual step (a Feature can't run anything on the host); the README documents it.
• Uses h4_require_root from helpers4-common 1.2.3.

Test plan

• devcontainer features test --features peon-ping .
• devcontainer features test --features peon-ping --skip-autogenerated . (with_claude_dev scenario)
• Manual: start peon relay --daemon on a host, finish an agent turn in a container, hear the host's sound

Tested locally only with a fake relay (hooks registered idempotently, existing hooks preserved, category request sent, no error when the relay is down); Docker was not available to run the feature tests.

🤖 Generated with Claude Code

[github-actions]

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📋 Pipeline Status

	Job	Status
✅	🧾 Conventional Commits	passing
✅	🔖 Version Bump	passing
✅	🧪 Feature Tests	passing
✅	🧪 Scenario Tests	passing
✅	🐚 ShellCheck	passing

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_{🤖 Generated by @helpers4 CI • 2026-09-19}