[number field] Expand test coverage

[atomiks]

Expands Number Field test coverage to 100% across statements, branches, functions, and lines on merged jsdom and Chromium results, and removes the dead code the sweep uncovered.

Changes

• Added behavior tests for consumer-prevented focus, blur, change, and keydown defaults, single sign-character replacement, hidden-input focus and autofill, vertical scrubbing, virtual cursor wrapping, multi-touch pinch, non-primary pointer buttons, the iOS input mode, the Gecko pointer lock delay, and the missing-context errors.
• Restored the scrub area's isScrubbingRef guard on pointer move. Effects can tear down and re-run without unmounting under <Activity>, which clears the ref while isScrubbing stays true and re-attaches the listener, so a bare mouse move changed the value.
• Made getNumberLocaleDetails always return a decimal separator, which drops the optional-decimal branches in parseNumber and NumberField.Root.
• Replaced the willSetHome/willSetEnd pair in NumberField.Input with a single boundary value, removing an unreachable ?? null.
• Removed the commit fallbacks in the blur, keyboard, and wheel paths. setValue always records the stored value before those run, so the fallback could never fire.
• Removed the null guard in parseNumber, the redundant cursor null check in NumberField.ScrubArea, and the unused SCROLLING_POINTER_MOVE_DISTANCE constant.

[pkg-pr-new]

• base-ui-tanstack-start

• vite-css-base-ui-example

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/react@5280
  

  pnpm add https://pkg.pr.new/mui/base-ui/@base-ui/utils@5280
  

commit: 9794890

[code-infra-dashboard]

Bundle size

Bundle	Parsed size	Gzip size
@base-ui/react	▼-77B(-0.02%)	▼-14B(-0.01%)

Details of bundle changes

Performance

Total duration: 1,283.32 ms -137.51 ms^(-9.7%) | Renders: 78 ⁽⁺⁰⁾ | Paint: 2,025.83 ms -193.07 ms^(-8.7%)

Test	Duration	Renders
Menu mount (300 instances)	127.84 ms ▼-57.90 ms(-31.2%)	2 (+0)
Menu open (500 items)	62.84 ms ▼-24.32 ms(-27.9%)	12 (+0)
Combobox type — 500 items, narrows to ~11 (type "Row 25")	34.40 ms ▼-9.65 ms(-21.9%)	15 (+0)

12 tests within noise — details

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