fix: declare qbo skill dependencies

[maximilien]

Summary

• declare the qbo binary requirement in the skill frontmatter
• expose managed Homebrew and Go installers through the OpenClaw skill metadata contract
• retain the existing Markdown installation guidance for Windows and manual binary installs

This lets compatible skill hosts detect a missing QBO CLI and offer a reviewed installer instead of relying on prose parsing. The metadata follows the documented OpenClaw installer schema: https://docs.openclaw.ai/tools/skills#installer-specs

Validation

• make test (Go race suite)
• parsed the skill metadata and verified the missing qbo requirement plus installer choices

[voska]

Thanks for adding this, and sorry for the slow review. Declaring the binary requirement and installers is a useful improvement.

The module key is correct: OpenClaw's Go installer reads it directly. The Homebrew formula matches too. No change needed to either installer entry; CI still needs to pass before merging.