sync from GitHub a39d5b2: fix(client): 云端备份清空后本地索引失效自动转全量，修复增量复用死key导致blob_missing；versionCode 383

sync from GitHub c8523f8: feat(admin): one-click clear all V6 backups, merge backup panels, logs API

fix: 修复v6备份blob静默丢失 + 新增日志查询API key功能

sync from GitHub 1362c47: feat: update version code and enhance backup system

sync from GitHub 1c1ef96: feat: implement v6 backup storage layer with content-addressable blobs, snapshot management, and garbage collection