Add Shopify Expert Agent chat mode.

[Naikabg]

Pull Request Checklist

• I have read and followed the CONTRIBUTING.md guidelines.
• My contribution adds a new instruction, prompt, or chat mode file in the correct directory.
• The file follows the required naming convention.
• The content is clearly structured and follows the example format.
• I have tested my instructions, prompt, or chat mode with GitHub Copilot.
• I have run node update-readme.js and verified that README.md is up to date.

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Description

This contribution adds a comprehensive Shopify Expert chat-mode that provides specialized assistance for Shopify development. The chat-mode covers:

• Theme Development: Liquid templating, Online Store 2.0, sections, blocks, and schema configuration
• App Development: Building Shopify apps with Node.js, React, Remix, and App Bridge
• API Integration: GraphQL Admin API, Storefront API, webhooks, and rate limit management
• Performance Optimization: Image optimization, lazy loading, Core Web Vitals, and bundle size reduction
• Advanced Features: Shopify Functions, checkout extensions, metafields, metaobjects, and custom data modeling

The chat-mode includes extensive code examples for common scenarios like AJAX cart implementation, custom sections with schema, GraphQL queries, and Shopify Functions. It follows the same high-quality structure as existing expert chat-modes and provides actionable guidance following Shopify best practices.

Usage Context: This chat-mode is ideal for developers building Shopify themes, custom apps, or headless commerce solutions who need expert guidance on Shopify's APIs, Liquid templating, and modern development workflows.

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Type of Contribution

• New instruction file.
• New prompt file.
• New chat mode file.
• Other (please specify):

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Additional Notes

File Location: chatmodes/shopify-expert.chatmode.md

• Contains 682 lines of comprehensive guidance, code examples, and best practices
• Covers both traditional Shopify theme development and modern app development approaches

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By submitting this pull request, I confirm that my contribution abides by the Code of Conduct and will be licensed under the MIT License.