feat: Add 57 skills from vibeship-spawner-skills

Ported 3 categories from Spawner Skills (Apache 2.0):
- AI Agents (21 skills): langfuse, langgraph, crewai, rag-engineer, etc.
- Integrations (25 skills): stripe, firebase, vercel, supabase, etc.
- Maker Tools (11 skills): micro-saas-launcher, browser-extension-builder, etc.

All skills converted from 4-file YAML to SKILL.md format.
Source: https://github.com/vibeforge1111/vibeship-spawner-skills

skills/shopify-apps/SKILL.md

@@ -0,0 +1,42 @@
+---
+name: shopify-apps
+description: "Expert patterns for Shopify app development including Remix/React Router apps, embedded apps with App Bridge, webhook handling, GraphQL Admin API, Polaris components, billing, and app extensions. Use when: shopify app, shopify, embedded app, polaris, app bridge."
+source: vibeship-spawner-skills (Apache 2.0)
+---
+
+# Shopify Apps
+
+## Patterns
+
+### React Router App Setup
+
+Modern Shopify app template with React Router
+
+### Embedded App with App Bridge
+
+Render app embedded in Shopify Admin
+
+### Webhook Handling
+
+Secure webhook processing with HMAC verification
+
+## Anti-Patterns
+
+### ❌ REST API for New Apps
+
+### ❌ Webhook Processing Before Response
+
+### ❌ Polling Instead of Webhooks
+
+## ⚠️ Sharp Edges
+
+| Issue | Severity | Solution |
+|-------|----------|----------|
+| Issue | high | ## Respond immediately, process asynchronously |
+| Issue | high | ## Check rate limit headers |
+| Issue | high | ## Request protected customer data access |
+| Issue | medium | ## Use TOML only (recommended) |
+| Issue | medium | ## Handle both URL formats |
+| Issue | high | ## Use GraphQL for all new code |
+| Issue | high | ## Use latest App Bridge via script tag |
+| Issue | high | ## Implement all GDPR handlers |