Support component composition and reuse

[akonan]

Description

Add syntax for defining reusable components and composing them.

Proposed Syntax

Define Component

<!-- Define in components/button.md -->
## Button {#component}
[{{text}}]{.{{variant}}}

Use Component

<!-- Use in main mockup -->
<Button text="Submit" variant="primary" />
<Button text="Cancel" variant="secondary" />

Features

• Component library support
• Props/parameters
• Default values
• Slot/children support
• Component variants

Implementation

• Component registry
• Template interpolation
• Recursive rendering

Priority

Medium

Labels

enhancement, components, reusability