remove clipboard.js use vanilla javascript

[mlinksva]

Fixes #1138

[Copilot]

Pull request overview

This PR removes the clipboard.js external library dependency and replaces it with a vanilla JavaScript implementation, addressing issue #1138. The change reduces dependencies and uses modern browser APIs for clipboard functionality.

Key Changes:

• Implemented native clipboard functionality using navigator.clipboard.writeText() with fallback to document.execCommand('copy')
• Replaced clipboard.js event-based architecture with direct event listeners for click, mouseleave, and blur events
• Removed all clipboard.js vendor files and updated build configuration accordingly

Reviewed changes

Copilot reviewed 4 out of 13 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
assets/js/app.js	Replaced clipboard.js with vanilla JavaScript implementation using modern Clipboard API and execCommand fallback
_includes/footer.html	Removed clipboard.min.js script tag
bower.json	Removed clipboard dependency from bower configuration
_config.yml	Removed clipboard test directory from exclusions
.gitignore	Removed clipboard vendor directory exclusions
assets/vendor/clipboard/*	Deleted all clipboard.js vendor files (dist, documentation, configuration)

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