DataViews: Store the clicked calendar day in the datetime control across timezones

[jorgefilipecosta]

When the site timezone is behind the timezone the calendar is rendered in, clicking a day in the Datetime DataForm control's calendar stores the previous day. The calendar hands back the clicked day as a Date built from its displayed day, and converting that instant with dateI18n( 'Y-m-d', … ) re-expresses it in the site timezone, shifting it across midnight. For example, with the site timezone at UTC and a browser at UTC+1, clicking "October 14" stores October 13.

The fix reads the selected day through the date's own fields with format( newDate, 'yyyy-MM-dd' ), the same way the plain date control already reads its selections, and uses the start of the selected day as the fallback when there is no time to preserve. The time of an existing value is still preserved in the site timezone.

Discovered while preparing #81635. A broader follow-up worth considering separately: for sites configured with a manual offset (no named timezone), the calendar's timeZone prop falls back to the browser timezone, so day highlighting and the "today" marker also render in the wrong frame across the date controls; rendering the calendar in the site timezone would need an offset-based timeZone value and has browser-compatibility implications, so it is intentionally out of scope here.

Testing Instructions

1. Make sure the site timezone differs from your browser's, with the site behind — for example set the site to UTC+0 (or an offset like UTC-5) in Settings > General while your machine is ahead of it.
2. Enable the DataForm inspector experiment under Gutenberg > Experiments ("Block fields: Show dataform driven inspector fields on blocks that support them").
3. Open a post in the editor, open the Settings sidebar, and click the Date field.
4. Click a day in the calendar. The datetime input above the calendar (and the value shown in the sidebar) should show the day you clicked. Without this change, they show the previous day.

The unit test can be run with:

npm run test:unit -- packages/dataviews/src/components/dataform-controls/test

Before (video): clicking October 14 stores October 13.

After (video): clicking October 14 stores October 14.

Note: this branch and #81635 both touch datetime.tsx and add to the same test file, so whichever lands second needs a trivial rebase.

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[github-actions]

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[github-actions]

Size Change: +23 B (0%)

Total Size: 7.74 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-editor/index.min.js	470 kB	-6 B (0%)
build/scripts/edit-site/index.min.js	335 kB	+11 B (0%)
build/scripts/editor/index.min.js	532 kB	+10 B (0%)
build/scripts/media-utils/index.min.js	154 kB	+8 B (+0.01%)

_{compressed-size-action}

[github-actions]

Flaky tests detected in 6cee1c2.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/32280805629
📝 Reported tests:

Should save the changes in /test/e2e/specs/editor/plugins/wp-editor-meta-box.spec.js, passed after 2 failed attempts.

TimeoutError: page.waitForFunction: Timeout 10000ms exceeded.
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/plugins/wp-editor-meta-box.spec.js:34:14
TimeoutError: locator.click: Timeout 10000ms exceeded.
Call log:
  - waiting for locator('role=button[name="Visual"i]')

    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/editor/plugins/wp-editor-meta-box.spec.js:33:55

edits a scope guideline after a reload in /test/e2e/specs/admin/guidelines.spec.js, passed after 1 failed attempt.

Error: apiRequestContext.fetch: socket hang up
Call log:
  - → GET http://localhost:8889/wp-json/wp/v2/knowledge?per_page=100&context=edit&status=publish%2Cdraft%2Cprivate
    - user-agent: Playwright/1.62.1 (x64; ubuntu 24.04) node/20.20 CI/1
    - accept: */*
    - accept-encoding: gzip,deflate,br
    - X-WP-Nonce: 2ac0306aad
    - cookie: wordpress_test_cookie=WP%20Cookie%20check; wordpress_logged_in_23778236db82f19306f247e20a353a99=admin%7C1787332965%7CziwrJON5AK9zvfrdrPuRsc06XLb4bzVX15wTnzhHYQW%7C1103b247d6d6e1aa8ad847ad09b28bb6c8058be1c4b9225a4d55d0cb6607dee1; wp-settings-time-1=1787160166

    at RequestUtils.rest (/home/runner/work/gutenberg/gutenberg/packages/e2e-test-utils-playwright/src/request-utils/rest.ts:112:39)
    at deleteAllGuidelines (/home/runner/work/gutenberg/gutenberg/test/e2e/specs/admin/guidelines.spec.js:12:34)
    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/admin/guidelines.spec.js:100:9

should allow user to add and remove multiple local font files in /test/e2e/specs/admin/font-library.spec.js, passed after 1 failed attempt.

Error: expect(locator).toBeVisible() failed

Locator: getByLabel('Exo 2 Semi-bold Italic')
Expected: visible
Timeout: 5000ms
Error: element(s) not found

Call log:
  - Expect "toBeVisible" with timeout 5000ms
  - waiting for getByLabel('Exo 2 Semi-bold Italic')

    at /home/runner/work/gutenberg/gutenberg/test/e2e/specs/admin/font-library.spec.js:58:6

[ciampo]

Closing as superseded by #81498 (which should cover the same fix + additional improvements).

@jorgefilipecosta please check #81498 and feel free to re-open this PR in case I misinterpreted