Add agent skills (skill toolset)

Agent skills are markdown instruction packs the model loads on demand (load_skill, etc.). They live under internal/skills/skills/<name>/SKILL.md, are embedded into the binary, and exposed through ADK skilltoolset on llmagent.Config.Toolsets — separate from proto-backed Tools (add-tool / add-lro).

Identify the agent module (go.mod) and entrypoint before editing. In Alis Build projects, read .alis/agents/AGENTS.md if it exists for product repo roots and neuron paths.

When to use

See the skill description (primary trigger). In short: runtime internal/skills/skills/*/SKILL.md + Toolsets, not neuron .agents/skills/, not proto tools.

When not to use

Architecture