#30711 fix(webviews): format three acpmux test files (base web-lint red)

Base red fix for feat-cmux-next: the tip watcher's web-lint has failed since about 09:46Z on vp fmt --check for three acpmux test files: backgroundTurns.test.tsx, subsessions.test.ts and summary/subagentOrder.test.ts. The base autofix at e3e35070f245 did not repair it (the red stayed through 4 tips). This is the formatter's own output for those three files; no test logic changes.

Checked first: no open or merged PR formats these files.

Changelog

none

Observed / Not run

• Observed: vp fmt --check in webviews/ at this head: all 3768 files pass. prepush-gate: no new violations.
• Skipped in the pre-push web lint, with the named reason: vp lint and vp check --no-fmt --no-lint exit 1 on the base fd34ef95aa2c as well (base reds; this PR touches neither).
• Not run: the webview test suites (formatting only).

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Summary by cubic

Fixes the web-lint failure on the feat-cmux-next tip by formatting three acpmux test files. These are the formatter's own outputs; no test logic changes.

• vp fmt --check now passes on all 3768 files in webviews/.
• The base autofix didn't repair the red, so this applies the formatter output directly.