* fix(database): snapshot SQLite backups online
Use SQLite's online backup API for downloadable backups and SQLite migration exports instead of checkpointing then reading the live database file. The regression test validates a backup made while writes continue.
* style(database): group SQLite driver imports
* fix(database): bound online backup retries
Use a single backup step and a bounded connection-acquisition/retry context. Tighten temporary-file cleanup and regression assertions while removing the unused checkpoint helper.
* test(database): cover existing backup destinations
* fix(database): harden SQLite snapshot lifecycle
Sweep interrupted snapshot directories at SQLite startup, keep rollback-journal backups incremental, and make caller-owned cleanup explicit. Reuse one scheduled Telegram snapshot across administrators and make the direct SQLite driver dependency explicit.
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Co-authored-by: PathGao <gaoyanbo@gaoyanbodeMacBook-Air.local>
PathGao