feat(compiler): v5 new docs-agent-skill output target

[johnjenkins]

What is the current behavior?

GitHub Issue Number: N/A

What is the new behavior?

docs-agent-skill output target

Generates an Agent Skill - SKILL.md + per-component reference files - describing your component library, so AI coding agents (Claude Code, Cursor, Codex, and 70+ others via npx skills add) can look up props, events, slots, and real usage examples.

Introduces a project-level src/usage/*.md convention for library-wide intro content (installation, theming, etc.), which feeds the skill's description.

Setup

// stencil.config.ts
export const config: Config = {
  outputTargets: [
    { type: 'docs-agent-skill' }, // > dist/skill/
  ],
};

Optional project-level intro (also powers the skill's auto-generated description):

<!-- src/usage/getting-started.md -->
# Getting Started

Install the library, then import the components you need.

From a consuming project, install the generated skill into whatever agent:

npx skills add node_modules/my-design-system/dist/skill

Output

dist/skill/
  SKILL.md
  components/
    my-button.md
    my-input.md

<!-- dist/skill/SKILL.md -->
---
name: my-design-system
description: Install the library, then import the components you need.
---

# my-design-system

## Usage

### Getting-started

# Getting Started

Install the library, then import the components you need.

## Components

- [my-button](components/my-button.md) — A clickable button component.
- [my-input](components/my-input.md) — A simple text input component.

<!-- dist/skill/components/my-button.md -->
# my-button

## Overview

A clickable button component.

## Properties

| Property  | Attribute | Description                | Type                       | Default     |
| --------- | --------- | --------------------------- | --------------------------- | ----------- |
| `variant` | `variant` | The button's visual style. | `"primary" \| "secondary"` | `'primary'` |

## Events

| Event           | Description                         | Type                 |
| --------------- | ------------------------------------ | --------------------- |
| `myButtonClick` | Emitted when the button is clicked. | `CustomEvent<void>`   |

## Usage

### Example-1

# Basic Usage

​```html
<my-button variant="primary">Click me</my-button>
​```

Documentation

Does this introduce a breaking change?

• Yes
• No

Testing

Other information