fix(sessions): prevent cleanup from deleting readable transcripts (#1…

fix(sessions): prevent cleanup from deleting readable transcripts (#123495)

* fix(sessions): make transcript archival atomic

* fix(sessions): stabilize SQLite archive CI

* test(gateway): synchronize lifecycle patch race

* fix(sessions): finish archive recovery accounting

* fix: key transcript archives by generation

Remeasure physical disk usage after archive publication so budget results and pruning use the bytes actually present on disk.

Refs oc-8e9

* fix(sessions): normalize doctor archive generations (oc-a28)

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Co-authored-by: Josh Lehman <550978+jalehman@users.noreply.github.com>