Drop zone now has three explicit visual states: empty (default cloud +
instructions), ready (large file icon with a checkmark badge, filename in
big, size + click-to-replace + remove button, solid emerald border and
tinted background), and error (red icon + message, auto-clears after
2.5s). Covers both drag-drop and click-to-browse flows, validates size
client-side, and scales up slightly during dragover.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dtoro
b1ff3ca80f