Add a new Chat checkbox to toggle timestamps for tool, reasoning, and justification headers (default off).
Keep assistant message footer timestamps visible and switch to a more readable compact date format.
Preserve hover timestamp overlays with chat-surface background when the new setting is enabled.
* feat(chat): add shared activity timestamp formatter
* feat(chat): pass assistant created timestamp to message body
* feat(chat): render footer timestamp beside elapsed time
* feat(chat): pass timing metadata in reasoning text blocks
* feat(chat): propagate justification timing to timeline block
* feat(chat): show thinking duration with hover end time
* feat(chat): reveal tool end time on activity hover
Bohdan Triapitsyn