Support the open Agent Skills standard

[endymion]

Summary

• add support for the open Agent Skills standard so we can reuse community-defined capabilities
• integrate https://agentskills.io/home so Tactus agents can load prebuilt skills and better share workflows

Benefits

• unlocks a catalog of off-the-shelf skills
• reduces duplication for new capabilities by reusing existing skills
• aligns the project with an interoperable format that other agent platforms already adopt

Additional Context

See the standard homepage for details: https://agentskills.io/home