Use the existing session-export, transcription and DingTalk owners.
Remove unused setup/watchdog helpers and the no-op package migration
hook. No package overrides it; user-state migrations keep their own
existing owners. Keep version-change installation coverage and the
scheduled external plugin compatibility blocks.
Verified with the real adapter, transcription, session-snapshot and
PM core suites. No live messaging service or user-state operation.
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