Fix Copy button fails in Safari

[fcakyon]

Summary

• The "Copy page in Markdown format" button works in Chrome, Edge, and Firefox but fails in Safari with "Failed" message
• Safari has stricter Clipboard API security that rejects writes when async operations (like fetch) occur before the clipboard write
• Switch from navigator.clipboard.writeText() to ClipboardItem API which reserves clipboard permission at click time while content loads asynchronously
• This approach works across all modern browsers including Safari

Test

Tested on Safari 18 - button now shows "Copied!" and markdown content is correctly copied to clipboard.

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Fixes Safari clipboard copy failures by switching to ClipboardItem-based async content generation. 🧩

📊 Key Changes

• Refactored the markdown fetch/format logic into an async getContent() helper
• Replaced navigator.clipboard.writeText(...) with navigator.clipboard.write([new ClipboardItem(...)])
• Ensured front-matter stripping and title/source header generation remain intact

🎯 Purpose & Impact

• Improves cross-browser compatibility, specifically resolving copy-button failures in Safari 🧭
• Provides more reliable clipboard writes for generated markdown content 📋
• Keeps user experience consistent by maintaining the same “Copied!” feedback behavior ✅

[UltralyticsAssistant]

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🔍 PR Review

_{Made with ❤️ by Ultralytics Actions}

Looks clean—no issues found based on the diff. The refactor to async content generation and ClipboardItem usage appears safe and consistent with existing behavior.