Models are always re-pushed server-side since Draco compression changes
the file size, making client/remote size comparison unreliable.
Textures are still compared by size (not compressed, reliable).
Client-side diff now only flags models as 'new' if absent from remote,
and never as 'changed' (server handles the actual push decision).
Git LFS stores pointer files whose SHA differs from the actual blob SHA,
causing false-positive diffs on every upload. Switching to file size
comparison resolves this for LFS-enabled repos.
Also replaces the inline error message with a dedicated NoChangesModal
when no differences are detected, offering cancel (reset) or modify
(close modal) actions.
Tom Boullay