feat(export): add built-in Export options (PDF, DOC, HTML) to Markdown Live Preview

[arindam-sahoo]

I've been using Markdown Live Preview for the past three years, and it’s been one of my go-to tools for quick markdown editing and previews.
However, one recurring inconvenience has been the lack of an export option.

Whenever I need to save my markdown as a document, I’ve had to:

• Manually copy the rendered preview
• Paste it into a Word file or another editor
• Format and save it as a .doc or .pdf

This process works, but it breaks the otherwise smooth, in-browser workflow.

💡 Proposed Solution

Add native Export functionality that allows users to directly:

• Download as HTML
• Export as PDF
• Save as DOC

✅ Expected Benefits

• Faster document sharing and saving
• Better productivity for writers, developers, and note-takers
• Keeps the tool self-contained and privacy-friendly

[arindam-sahoo]

@tanabe Had been months using this tool but discovered today itself that this project is open source, so I wanted to contribute back to it — especially since I’ve been using it regularly for a long time. Had raised a PR, would love to get some reviews on it.
And Thanks Buddy, I might not need it every day, but it’s definitely one of the handiest tools I rely on.

[AlexFeng10000]

testing testing testing