[AkashNemade16]

Closes #10683

Preserve the last digit when typing a date moves focus to the next field. The issue's zh-TW examples currently produce August 1 instead of August 5, or September 3 instead of September 30.

Typing the last digit of a segment moves focus synchronously. When the next segment is in the other field of a DateRangePicker, the blur runs confirmPlaceholder() in the same event with a stale displayValue. useDateFieldState now keeps the latest displayValue in a ref. The setter updates it synchronously, so confirmPlaceholder reads the latest edit during the same event. A regular useEffect resyncs the ref after rendering, including controlled value changes. No layout effect is added to the date-field state, and Virtualizer remains unchanged.

Regression tests cover automatic focus advancement, invalid-date clamping, controlled/uncontrolled edits, and clearing or replacing a controlled value during an unfinished edit. Existing docs and stories still apply. AI assistance: GitHub Copilot and OpenAI Codex.

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices
• I understand every change in this PR and can explain why it's there.
• If AI-assisted, I followed our AI contribution guidance and pointed my assistant at AGENTS.md.

📝 Test Instructions:

The regression coverage includes both fields, leading-zero and invalid days, controlled/uncontrolled edits, displayed and committed values, automatic focus advancement, and clearing or replacing the controlled value during an unfinished edit.

Node 24.15.0, Yarn 4.18.0; review fix at 8fbe96f2e.

Command	Result
yarn test --maxWorkers=2 --watchman=false	Passed: 385 suites, 8,478 tests, 262 snapshots; 16 tests skipped.
yarn test:ssr --watchman=false	Passed: 60 suites, 74 tests.
yarn lint	Passed: format check, type check, oxlint, package lint and constraints.
yarn test:browser --project=chromium-desktop --project=webkit-desktop --maxWorkers=1 --no-file-parallelism	Not green: 36 files passed, 1 failed, 9 skipped; 294 tests passed, 1 failed, 33 skipped. WebKit opening assertions failed intermittently (Modal, and DateRangePicker in one combined run).

Validation notes: the initial SSR attempt could not bind its local server inside the sandbox; a later run had one startup connection reset, and the complete retry passed. The all-browser run could not connect to Firefox. A full WebKit-only run with the final changes passed 137 tests, skipped 26, and failed the Modal opening test; DateRangePicker passed in that run. One comparison run against the unchanged PR head passed all 138 WebKit tests, so the browser failures remain unresolved rather than being classified as pre-existing. The unit run exited successfully with a worker teardown warning. No Chromatic or manual screen-reader/mobile checks were run.

With locale="zh-TW", type 20260805 or 20260931 without tabbing. Expect August 5 or September 30 after focus advances. Repeat for the end field with a following focusable control inside the picker, and edit 15 to 07.

🧢 Your Project:

N/A - community bug fix.