[feature]: Option to copy description content as plain text (without Markdown formatting)

Is there an existing issue for this?

• I have searched the existing issues

Summary

Since PR #6675 introduced the MarkdownClipboard extension, copying text from the issue description always serializes content as Markdown. This means copying a simple sentence like "Deploy to production" results in clipboard content wrapped in backticks or other Markdown syntax.
CMD+C (or CTRL+C) on any text inside the description editor copies the content as Markdown-formatted text, including unwanted backticks, asterisks, and other symbols.
Provide one of the following:

• A keyboard shortcut (e.g. CMD+SHIFT+C) to copy as plain text
• A right-click context menu option: "Copy as plain text"
• A toggle in editor settings: "Copy as Markdown / Copy as plain text"
• Self-hosted
• macOS

Why should this be worked on?

When pasting description content into external tools (Jetbrains IDE, Slack, email, Google Docs, terminal), the Markdown symbols appear as raw characters and require manual cleanup. The current workaround is to paste into a plain text editor first, which adds unnecessary friction.