[BUG] VS Code extension: "Thought for Ns" timer keeps incrementing on already-completed turns

Title

[BUG] VS Code extension: "Thought for Ns" timer keeps incrementing on already-completed turns

Body

Description

In the VS Code extension, the "Thought for Ns" elapsed-time label on a thinking-only fold does not stop/re-collapse once its turn has actually completed. The timer keeps counting up in real time on a past, already-finished turn, even while the conversation has visibly moved on to later turns.

This is distinct from the "Claude hangs on thinking forever" reports (e.g. #38258, #32526) — the turn itself completes normally and produces real text output. Only the elapsed-time display on the now-finished turn's thinking fold fails to stop.

Steps to reproduce

1. Send a message that triggers a thinking-only fold (no visible text before the tool/response).
2. Wait for that turn to fully complete (real text response is shown, turn is done).
3. Send a follow-up message and let the conversation continue to a new turn.
4. Observe the previous, already-completed turn's "Thought for Ns" label — the seconds keep incrementing in real time instead of staying fixed / re-collapsing.

Expected behavior

Per the 2.1.216 changelog entry ("thinking-only folds show 'Thought for Ns' and re-collapse when their turn completes"), the label should freeze/re-collapse once the turn is done.

Actual behavior

The elapsed-time label on a completed turn continues to increment, seemingly indefinitely, while the conversation has already moved on.

Environment

• claude --version: 2.1.233
• VS Code extension (anthropic.claude-code): 2.1.233 (same version, no mismatch)
• OS: macOS 14.5 (23F79)
• Updated to 2.1.233 on 2026-08-14; symptom first noticed 2026-08-17

Additional notes

Possibly related: 2.1.217's changelog entry mentions "the thinking status row re-rendering every few seconds to update elapsed time and token counts" — this periodic re-render may not be getting torn down / cancelled when a turn's fold is supposed to re-collapse (the 2.1.216 fix), leading to a stale timer that keeps ticking on a completed turn.