The old decodeBase64 implementation tried atob() first which returns
garbled text for UTF-8 content (e.g., Chinese characters), and only
fell back to correct UTF-8 decoding when atob() threw an exception
(which it doesn't for valid base64).
Changes:
- Add encodeBase64/decodeBase64 utilities to web/src/lib/utils.ts
using TextEncoder/TextDecoder for proper UTF-8 support
- Update file.tsx to use shared decodeBase64 instead of buggy local impl
- Update files.tsx to use shared encodeBase64 instead of deprecated
escape/unescape approach
weishu