Feature: Add vue skill

[DaveDev13]

Adds a vue:components skill that converts Stitch HTML designs into Vue 3 Single File Components using the Composition API. Closed #50

Skill structure

vue-components/
├── SKILL.md — Core instructions & workflow
├── README.md — Install & usage
├── package.json — Validator dependencies
├── scripts/fetch-stitch.sh — Stitch asset downloader
├── scripts/validate.js — AST validator (defineProps & hex checks)
├── resources/architecture-checklist.md — Quality gate checklist
├── resources/component-template.vue — Starter SFC template
├── resources/style-guide.json — Theme token reference
└── examples/gold-standard-card.vue — Reference implementation

Modeled after the existing react-components skill, adapted for Vue 3's SFC format, Composition API conventions, and Vite project structure.

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