UI: Set Calendar text direction automatically

[ciampo]

Follow-up to #81814.

What?

Makes Calendar and RangeCalendar set their default text direction automatically.

Why?

The en-US formatting fallback made calendars LTR on RTL sites when locale was omitted or unsupported, such as skr on Node 20.

How?

An explicit dir still wins. A supported locale determines direction. Otherwise, the calendars use the WordPress text direction while date formatting continues to fall back to en-US.

Consumers that intentionally follow their surrounding interface direction, such as DataViews, continue to pass an explicit dir independently of their date-formatting locale.

Testing Instructions

1. Open the default Calendar and RangeCalendar stories.
2. Leave locale unset and switch the Storybook RTL toolbar between LTR and RTL. Confirm each calendar follows the toolbar direction.
3. In LTR mode, select Persian (locale code). Confirm the calendar is RTL.
4. Set dir to ltr. Confirm the explicit override wins.
5. Open the DataViews/FieldTypes date story and switch the toolbar to RTL. Confirm the calendar follows the RTL interface even though its dates remain formatted in English.

Testing Instructions for Keyboard

Focus a day and use the Left and Right Arrow keys. Confirm focus follows the calendar direction in both LTR and RTL modes.

Use of AI Tools

Codex was used to implement and test the change and to draft this pull request description.

[github-actions]

Size Change: +152 B (0%)

Total Size: 7.9 MB

📦 View Changed

Filename	Size	Change
build/scripts/block-editor/index.min.js	475 kB	+74 B (+0.02%)
build/scripts/edit-site/index.min.js	380 kB	+23 B (+0.01%)
build/scripts/editor/index.min.js	577 kB	+47 B (+0.01%)
build/scripts/media-utils/index.min.js	198 kB	+8 B (0%)

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[github-actions]

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Co-authored-by: ciampo <mciampini@git.wordpress.org>
Co-authored-by: simison <simison@git.wordpress.org>
Co-authored-by: ntsekouras <ntsekouras@git.wordpress.org>

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[ntsekouras]

It seems removing the dir from the date controls changes behavior for consumers outside wp-admin. @wordpress/date defaults its locale to en, so when nothing calls wp.date.setSettings (e.g. Storybook), the calendar now takes its direction from en and isRTL() is never consulted. You can see it in Storybook: open the DataViews/FieldTypes date story, toggle the direction in the toolbar and the calendar stays LTR while everything else flips.

Trunk

Here

Should we preserve the isRTL consulting?

[ciampo]

That makes sense, it's an angle I hadn't considered.

I restored the explicit dir props in dataviews. Now Calendar keeps its locale-based default, while DataViews intentionally follows the surrounding interface direction independently of its date-formatting locale.

I also added a regression test for the reported case. The DataViews/FieldTypes date story should now follow the RTL toolbar again while keeping its English date formatting.

Thank you for flagging it!

[ntsekouras]

@ciampo I disabled the auto-merge because I was reviewing and noticed this.