Cumulative token widgets over-report ~1.84x (upstream sirmalloc#549) — fix in our tree #8

Work item mirroring upstream sirmalloc/ccstatusline#549 — "Token widgets over-report ~1.84x: one JSONL entry per content block is counted per API call".

Problem: upstream writes one JSONL entry per content block sharing one message.id; the cumulative token widgets (Tokens Input / Output / Total) sum every entry, over-reporting by up to ~1.84x.

Already fixed in our tree (partial): the Tokens Last Turn widget (PR #1) groups entries by message.id and keeps the max output_tokens per API call; entries without an id start a new group; streaming partials resolve to the finalized value; sidechain/API-error rows are excluded. Verified on a synthetic sirmalloc#549-shaped transcript: exact Turn: 16.5k vs inflated cumulative Total: 49.3k on the same 3-entry id group.

Remaining work: apply the same grouping to the cumulative token path in getTranscriptAnalysis so Tokens Input/Output/Total stop over-reporting.

Acceptance: synthetic sirmalloc#549-shaped transcript yields exact cumulative totals; bun test green; no behavior change for transcripts without duplicate-id entries.

Status: not started.