TUI turn token summary mixes turn sums and last-step values on one line

Description

With debug.turn_tokens enabled, each completed turn renders a collapsed summary line:

+ Tokens: 13 steps · 138,541 new · 136,448 cached · 137,605 total

#41922 deliberately mixed units here: new is summed across all steps of the turn, while cached and total are the final step's values ("summed new tokens across steps, and the final step's cached/total figures"). Nothing on the line marks that distinction, so the three numbers read as the same kind of aggregate when they aren't — for every individual step new + cached = total, but on the summary line it looks like a broken equation.

This is the same unlabeled mixing of usage totals and context-state numbers that #36515 flagged on the desktop counter.

Expected behavior

All three figures on the summary line should use one consistent unit (turn-level sums), since the last step's context is already visible in the expanded per-step table and on the status bar. Alternatively, keep last-step values but label them explicitly.

Environment

• opencode v2 TUI, debug.turn_tokens enabled