Add comprehensive GitHub Copilot instructions for project guidelines and best practices

Author: kosiew

.github/copilot-instructions.md

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+# GitHub Copilot Instructions
+
+This document provides guidance for GitHub Copilot when working with this JavaScript project.
+
+## Project Overview
+
+This repository contains Tampermonkey scripts written in JavaScript. These scripts enhance user experience on various websites by adding custom functionality through browser extensions.
+
+## Coding Standards
+
+- Use modern JavaScript (ES6+) features where appropriate
+- Follow strict mode with `"use strict"` in all scripts
+- Use camelCase for variable and function names
+- Use meaningful variable and function names that describe their purpose
+- Keep functions small and focused on a single responsibility
+- Add proper error handling with try/catch blocks for operations that might fail
+- Avoid global variables; use closures and IIFEs to prevent namespace pollution
+
+## Documentation
+
+- Always include comprehensive JSDoc comments for functions
+- Document parameters and return values
+- Include examples where helpful
+- Maintain the UserScript headers with appropriate @match directives
+- Document DOM selectors used and why they were chosen
+
+## Best Practices
+
+- Prioritize performance with efficient DOM operations (minimize reflows and repaints)
+- Use querySelector/querySelectorAll instead of older DOM selection methods
+- Add descriptive console logs for debugging but comment them out in production
+- Use event delegation where appropriate
+- Clean up event listeners and observers when no longer needed
+- Test scripts across different browsers and versions
+
+## Project-Specific Guidelines
+
+- All scripts should follow the Tampermonkey metadata block format
+- Scripts should be self-contained and not rely on external libraries when possible
+- Always provide visual feedback to users when actions are performed (like copying to clipboard)
+- Consider adding user configuration options for flexible scripts
+
+## Testing
+
+- Test scripts manually on the target websites
+- Verify scripts work with different site layouts and states
+- Consider adding version checking to handle website structure changes
+
+## Security Considerations
+
+- Don't store sensitive information in localStorage or sessionStorage
+- Sanitize any user input
+- Be cautious when injecting HTML content to avoid XSS vulnerabilities
+- Don't expose private API tokens or credentials in your scripts