Reworked static/style.css to follow the same visual language as
lumeex's back office (near-black background, cyan accent, gradient
pill buttons, translucent bordered panels) instead of the previous
generic dark-teal theme. Dropzones now use a dashed border while
empty, turning solid once a file is picked. Also fixes a stale CSS
selector (.dropzone label.tag) that never matched the actual markup
(a <span>), so the SDR/HDR tag labels were unstyled before.
Adds Gitea and GitHub repo links in the footer, using the same icons
and link pattern as lumeex.
Djeex