pangxiaobin/MarkCardStudio ? reverse-engineered prompt

Build me a desktop app that turns Markdown into polished social media cards and PDFs, with a live editor and preview side by side. I want to paste or open a Markdown file, have it split into pages automatically, and be able to tweak the page breaks, reorder pages, and choose from a few nice visual styles and background options. It should support common content like code blocks, tables, KaTeX formulas, Mermaid diagrams, images, and callouts, then export everything as PNG, JPG, a long image, or a multi page PDF.

Please make it feel local first, so files, settings, images, and exports stay on my computer. Add presets for common post sizes like Xiaohongshu, Douyin, Weibo, and square posts, plus an easy way to switch between English and Chinese. If you need current docs for any tool or library, look them up online.