Remove all local file imports referencing ../../../tu/ and
../../assets/ directories. Replace with OSS muban prefix URLs:
https://stringtest.oss-cn-hangzhou.aliyuncs.com/muban/
This fixes build failure on server (missing local image files)
and ensures images load from centralized OSS storage.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>