Same threading as prLinks: the cache-level title (last ai-title entry)
rides onto SessionSummary in both the Claude and generic provider
pipelines, and the sessions table gains a TITLE column (truncated at 38
chars, empty when a transcript never produced one, as subagent
transcripts typically do not). JSON rows carry it verbatim. Groundwork
for titles in the context browser, desktop Sessions view, and payload.
Co-authored-by: reviewer <review@local>