DetailsDialog is a centered SelectList over the five transcript-detail
states (three tool-card phases, reasoning shown/hidden); it preselects
the current phase, marks both current values, applies on Enter, and
cancels on Esc/Ctrl+C. Width is the new detailsDialogWidth config key.
The argument grammar is unchanged and shares the same setters.
/details reports the transcript detail state bare, jumps tool cards to
collapsed|expanded|hidden, and sets or toggles reasoning blocks, sharing
the closure state behind Ctrl+O/Ctrl+R via setToolsVisibility/setReasoning.
Also fixes a replay defect the reasoning rebuild exposed: rebuildTranscript
reused a settled StreamingAssistantComponent for a later assistant/message
of the same step, overwriting the earlier content; the settled check now
lives in renderEvent for both live and replay paths (untrusted-controls
re-recorded with the previously dropped content present).
