pikuri-skills

pikuri-skills implements the Agent Skills standard (agentskills.io) for pikuri-core agents: a +Pikuri::Skill::Catalog+ that discovers skill folders under .pikuri/skills, .claude/skills, and .agents/skills; a +Pikuri::Skill::SkillTool+ that loads a skill's body on demand; and a +Pikuri::Skill::Extension+ that wires both into a +Pikuri::Agent+ via +c.add_extension(...)+ in the +Agent.new+ block.