4939011b0d
Raw byte truncation at 200 bytes splits multi-byte codepoints (Chinese characters are 3 bytes), producing invalid UTF-8 that downstream filename validation (utf8.ValidString) rejects with "文件名包含非法字符". Peel trailing bytes via DecodeLastRuneInString until the last rune is complete. Same latent bug and fix as the Yuque connector's sanitizeFileName.