feat: allow hiding skills by name via config (disabled_skills)

Problem

Many setups share a generic skill directory across tools (for example ~/.agents/skills/). Those directories often contain skills that are useful for other agents but should not appear in Kimi at all — not in the model listing, not via the Skill tool, and not in the slash menu.

Today the closest options are incomplete for that case:

• Skill frontmatter disableModelInvocation: true only blocks automatic model invocation; the skill can still be slash-invoked and still shows up in listings.
• A permission deny rule for Skill(...) can block the tool call, but the skill name can still remain visible in the model listing.
• Removing or renaming files on disk breaks other tools that intentionally share the same directory.

Proposed solution

Add an optional top-level disabled_skills array in config.toml:

disabled_skills = ["grok-delegation", "pi-delegation"]

Behavior when a name matches (case-insensitive):

• Hidden from model skill listing
• Rejected by the Skill tool
• Hidden from the slash menu / user activation paths
• Files remain on disk for other tools

After editing, /reload or a new session applies the change.

Scope note

disabled_skills only covers the Skill surface. The agent may still reimplement a skill's workflow with other tools (for example Bash running a helper binary). Users who need that blocked should pair this with existing permission deny rules, which still apply in YOLO mode.

Why this fits Kimi Code

• Opt-in, empty default — no behavior change for existing users
• Complements rather than replaces disableModelInvocation and permission rules
• Supports shared multi-tool skill directories without forking the skill tree per product
• Same config surface for agent-core v1 and v2

Willingness to implement

I can open a focused PR with v1/v2 implementation, tests, bilingual docs, and a changeset if maintainers are open to this direction.

Start by tracing config.toml handling and the Skill tool, model skill listing, slash menu, and /reload entry points across agent-core v1 and v2. Done means case-insensitive disabled_skills names are hidden from listings and activation paths, rejected by Skill, preserved on disk, and applied after /reload or in a new session.