TriageProcessor.stop() previously only halted the polling loop, so
in-flight specify sessions and their reviewer subagents kept streaming
past shutdown. Extracted the existing global-pause teardown into
abortAndDisposeActiveSessions() and call it from stop() too.
aiMergeTask creates three sessions during a merge — autostash resolver,
in-merge verification fix agent, and pull-rebase conflict resolver — but
only the autostash one was registered via onSession. The other two are
now registered (with onSession threaded through pushToRemoteAfterMerge
into the rebase resolver chain), so ProjectEngine.stop() actually
disposes whichever merger session is running when shutdown lands.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
06b9a21ad5