fix(dockerfile): COPY fixtures into image

Commands /upload_* fell back to 'file not found' because the fixtures directory was never copied into the runtime image.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Dockerfile

@@ -30,6 +30,7 @@ COPY --from=builder /var/www/html/vendor /var/www/html/vendor
 COPY composer.json composer.lock ./
 COPY bin ./bin
 COPY config ./config
+COPY fixtures ./fixtures
 COPY public ./public
 COPY src ./src
 COPY storage ./storage