feat: add lazybox extension pack

[keys-i]

Summary

Expose the native lazybox executable through the shared launcher/dashboard with typed backend, action, and output choices. Snapshots run in the output pane; the interactive dashboard receives an exact direct-terminal command. No Bash or Python forwarding logic is added.

Stacked on #25. Native implementation: keys-i/tools#5, commit 30ef80f.

Scope

• bin/
• dev/
• lib/
• sys/
• Documentation or repository settings

Testing

bash run.sh --self-test
uv run dev/gui.py --self-test
git diff --check

macOS 26.5.2 ARM64, Python 3.14 via uv. The final dashboard self-test passes all 14 manuals, layout snapshots, keyboard paths, and fallbacks. Independent fallback gatekeeper: VERDICT: PASS.

Checklist

• The change is focused and contains no unrelated files.
• The code is clean and comments explain intent or risk.
• New or changed behaviour has a repeatable test or documented manual check.
• Help text and dependencies are current.
• Destructive behaviour and elevated permissions are clearly disclosed.
• No credentials, private data, or machine-specific paths are included.

Reviewer Notes

The pack resolves one validated executable from PATH and invokes it directly without a shell or implicit installer. Mutations remain inside Lazybox and require confirmation; backend calls use null stdin, an 8 MiB combined output cap, and a 30-second deadline. keys-tools is prepared but not published to PyPI. Revert 5ab2758 to remove this pack; this branch depends on #25.