[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 symb…