fix(useCombobox): preserve IME composition

[naveedsajjdawan]

What changed

• Ignore internal InputChange dispatches while the browser reports an active IME composition.
• Keep user-provided onChange/onInput handlers running during composition.
• Process the final, non-composing input event normally.
• Add a regression test covering intermediate Japanese input and the final committed value.

Why

With a controlled inputValue, dispatching every intermediate IME input event triggers Downshift state callbacks and rerenders the input. That can terminate the browser's composition session before users finish entering Japanese, Chinese, Korean, or other composition-based text.

Deferring Downshift's internal update until the committed input event preserves the native composition session without changing normal input behavior.

Verification

• npx jest src/hooks/useCombobox/__tests__/getInputProps.test.js --runInBand — 153 tests passed
• npx tsc --noEmit -p ./tsconfig.json — passed
• Prettier check for both changed files — passed

Fixes #1452