Skill studio for DeepSeek Harness

Key features

• skillmgr_list — list all skills with source, nested flag and invocation state.
• The frontmatter name key must match the skill name (kebab-case)
• skillmgr_get — view one skill's full detail (body + path + policy).
• skillmgr_save — save a full-body edit (frontmatter + markdown) back to the file.
• skillmgr_policy — enable/disable a skill (enabled master switch, or per-interface modelInvocable / userInvocable).