Reset clears the current block's elapsed time to zero and immediately
starts the timer. A shared compute_block_elapsed() utility (utils/timer.py)
handles the elapsed calculation in both the sessions and dashboard routers,
and correctly treats "reset" events as zero-elapsed restart markers so
page reloads after a reset show accurate times.
Layout: Start/Pause/Resume/Reset are grouped on the left; End Day sits
on the right via justify-content: space-between.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
