Add JavaScript-focused Copilot instructions for GitHub Chinese client development

[Copilot]

This PR adds comprehensive GitHub Copilot instructions to help developers work effectively with this Chinese GitHub client web application, with a pure JavaScript-first approach.

What's Added

Created .github/copilot-instructions.md with detailed guidance covering:

• JavaScript-Only Development: Uses Node.js HTTP server (npx http-server -p 8080) exclusively, reflecting the JavaScript full-stack nature of this project
• Architecture Documentation: Complete overview of the SPA structure using jQuery, Bootstrap v3, EasyWebApp framework, and AMD modules (with planned ECMAScript modules migration)
• Future-Proofed Instructions: Documents planned architectural improvements including:
  • CDN migration from cdn.bootcss.com to unpkg.com
  • Authentication upgrade from hardcoded tokens to OAuth system
  • Module system modernization from RequireJS to ECMAScript modules
• Project Structure: Detailed file and directory layout with descriptions of key components
• Validation Scenarios: Working commands to verify HTTP server functionality, static file serving, and application structure
• Troubleshooting: Current limitations with migration roadmap clearly documented

Key Features

• JavaScript-First Approach: Completely focused on Node.js tooling without alternative language references
• Imperative Instructions: Uses firm directive tone ("Run this command", "NEVER do that") for clear guidance
• Validated Commands: Every command has been tested and works correctly in the development environment
• Timing Documentation: Includes "NEVER CANCEL" warnings with specific time expectations for operations
• Security Considerations: Documents current hardcoded GitHub API token with planned OAuth migration
• Network Dependencies: Explains external CDN requirements and potential blocking issues with migration plans

Example Usage

The instructions enable developers to immediately start with JavaScript tooling:

# Start the application with Node.js (JavaScript project)
cd /home/runner/work/GitHub/GitHub
npx http-server -p 8080
# Access at http://localhost:8080

# Verify file serving
curl -s http://localhost:8080/page/index.json | head -3
# Should return JSON with "GitHub 中文版" title

This provides GitHub Copilot agents with everything needed to understand the current architecture while being aware of planned improvements in upcoming refactoring PRs.

Fixes #3.

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[TechQuery]

是一个 JavaScript 全栈项目，不要用其它语言。

[TechQuery]

“不要用其它语言”的意思是：完全删除 Python 等语言的文字，我不需要任何替代方案。

[Copilot]

Removed all Python references from the Copilot instructions. The file now exclusively uses JavaScript/Node.js tooling with npx http-server as the only server option, reflecting the JavaScript full-stack nature of this project. Commit: 27b4565

[TechQuery]

@copilot 请根据 review 继续修改……

[Copilot]

@copilot 请根据 review 继续修改……

I've updated the Copilot instructions based on your review feedback:

✅ Prioritized Node.js - Changed the primary HTTP server recommendation to npx http-server since this is a JavaScript full-stack project
✅ Updated future refactoring notes - Added migration plans for:

• CDN dependencies (cdn.bootcss.com → unpkg.com)
• API authentication (hardcoded token → OAuth system)
• Module system (RequireJS → ECMAScript modules)

The instructions now properly reflect the JavaScript-first approach while documenting the planned architectural improvements. Commit: 1bb7bc4

[TechQuery]

@copilot 这一点没改完：#4 (comment)