Redmine Markdown Preview & Converter

Adds a side-by-side GitHub-style Markdown preview to legacy Redmine editors.

> Detailed Description: This extension brings a modern Markdown editing experience to legacy Redmine environments that still rely on Textile formatting — no server changes required. > What it does: Side-by-side preview — a persistent split panel next to Redmine editors (issues, wiki, news, messages) renders Markdown or Textile in real time with GitHub-style formatting. Syntax selector — switch between Markdown and Textile mode with a single click. One-click conversion — convert Markdown → Textile or Textile → Markdown. A Restore button lets you undo the conversion instantly. Auto-detection — empty editors default to Markdown. Existing content is analyzed with a Textile-first / Markdown-assisted heuristic. Large pastes trigger re-detection automatically. Scroll synchronization — editor and preview scroll positions stay roughly synchronized. Syntax highlighting — code blocks are highlighted automatically. 100% local — all preview and conversion logic runs inside your browser. No data is ever sent to an external service. Supported Redmine pages: Issues (notes and descriptions), Wiki, News, Messages/Forums.