feat: initial Transmute app — universal client-side file converter

Full-stack client-side file converter with Next.js 15 static export.
Supports images (Canvas API), documents (mammoth/pdf-lib/jspdf),
audio/video (ffmpeg.wasm), and data formats (papaparse/yaml/xml).
Dark industrial UI with Space Grotesk + JetBrains Mono, animated
drop zone, glassmorphism file cards, progress rings, and ZIP downloads.
Zero server dependencies — files never leave the browser.

public/window.svg

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