Add skill frontmatter fields for slash command support

[pwang347]

No description provided.

[Copilot]

Pull request overview

This pull request adds support for slash command configuration fields to skills by extending the skill frontmatter with three new attributes: userInvokable, disableModelInvocation, and argumentHint. These fields enable skills to control their visibility and invocation behavior, similar to how agents work.

Changes:

• Added validation for userInvokable and disableModelInvocation attributes for skills
• Extended skill attribute list to include argumentHint, userInvokable, and disableModelInvocation
• Added autocompletion support for the new boolean attributes with true/false suggestions
• Implemented filtering to hide non-user-invokable skills from the slash command completion menu

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
promptValidator.ts	Adds validation calls for userInvokable and disableModelInvocation to skill validation, updates skill attribute list with three new fields, and adds localized descriptions for the new attributes
promptHeaderAutocompletion.ts	Extends autocompletion value suggestions to include skills for userInvokable and disableModelInvocation boolean attributes
chatInputCompletions.ts	Filters out skills with userInvokable=false from slash command completions to hide them from the / menu