feat: add shopify-development skill

- Add comprehensive Shopify development skill with validated GraphQL
- Fixed 4 mutations using Shopify MCP (fulfillmentCreate, appSubscription, etc.)
- Added shopify_graphql.py utilities with pagination & rate limiting
- Updated API version to 2026-01
- Added zircote/.claude as reference source

skills/shopify-development/scripts/requirements.txt

@@ -0,0 +1,19 @@
+# Shopify Skill Dependencies
+# Python 3.10+ required
+
+# No Python package dependencies - uses only standard library
+
+# Testing dependencies (dev)
+pytest>=8.0.0
+pytest-cov>=4.1.0
+pytest-mock>=3.12.0
+
+# Note: This script requires the Shopify CLI tool
+# Install Shopify CLI:
+#   npm install -g @shopify/cli @shopify/theme
+#   or via Homebrew (macOS):
+#   brew tap shopify/shopify
+#   brew install shopify-cli
+#
+# Authenticate with:
+#   shopify auth login