Restyle the UI to match lumeex's back-office look, add repo links

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.

docker/compose.yaml

@@ -8,8 +8,4 @@ services:
     container_name: instagram-hdr-web
     restart: unless-stopped
     ports:
-      - "5050:5000"  # host:container — change 5050 if that's taken too
-    # Put a reverse proxy (Traefik/nginx/SWAG) in front of this if you
-    # want it reachable outside your LAN — the Flask app itself has no
-    # auth and no rate limiting, so keep it internal-only or add both
-    # before exposing it further than your own network.
+      - "5050:5000"  # host:container — change 5050 if that's taken too