fix(vidstack): right-to-left layout and spoken time in the page's language

[aviahmorag]

Related:

No existing issue.

Description:

Makes sliders and the default layout's menus work in right-to-left pages (Hebrew, Arabic, Persian), and speaks times in the page's language. Today, in a dir="rtl" page:

• Horizontal sliders (time, volume, speed, quality, caption size, audio boost) still run left to right. Pointer, touch-drag and arrow keys are all measured from the left.
• Menu rows are pinned to the physical left (justify-content: left), and icons, hints, radio check marks and their indentation use physical margins and padding, so they sit on the wrong side.
• The back and submenu arrows point the left-to-right way, and the switch knob is positioned with an unanchored translateX, so it leaves the track.

Changes:

• SliderEventsController: a horizontal slider whose computed direction is rtl reads pointer position from the right edge, inverts touch-drag, and swaps ArrowLeft/ArrowRight. Up/Down, Home/End and vertical sliders are unchanged.

• default/sliders.css: horizontal sliders in :dir(rtl) are mirrored with scale: -1 1 (so the transforms Vidstack sets on the thumb and fill still apply), and the preview is mirrored back so its text and thumbnail read normally.

• default/menus.css: physical properties become logical ones (margin-inline-*, padding-inline-*, inset-inline-start, border-inline-start, justify-content: flex-start). The two menu arrows flip in :dir(rtl), and the switch knob is anchored to the right and moves left.

• Spoken time: formatSpokenTime(duration, lang?) spells the units with Intl.DurationFormat in the given language when the browser has it, so plurals follow CLDR (Arabic "دقيقتان", Russian "21 минута 3 секунды"). The time slider's value text, the announcer's seek announcement and the chapters menu pass the closest lang attribute. Without a lang, or without Intl.DurationFormat, the output is the current "1 min 23 sec".

• The time slider gets a translations prop for the two words CLDR has no pattern for, out of and live; both default layouts pass theirs, and DefaultLayoutWord gains the two words.

Left-to-right rendering is unchanged. One visible difference in English: on a page with lang="en", the screen-reader text now says "6 seconds out of 12 seconds" instead of "6 sec out of 12 sec".

Ready?

Yes.

Anything Else?

Before: the Accessibility menu in Hebrew with dir="rtl" alone. The back arrow runs into the title and the switch knobs sit outside their tracks.

After: the same menu as the mirror image of the left-to-right one.

Tested in WebKit (Playwright) and Safari with React + DefaultVideoLayout in a dir="rtl" page:

• Clicking 10% from the left of the time slider seeks to 90%.
• Clicking the left side of the volume slider raises the volume; ArrowLeft raises it and ArrowRight lowers it.
• Every settings menu level was compared with the left-to-right one and is its mirror image.
• Left-to-right menus are pixel-identical before and after, apart from hover state.
• Time slider value text on a lang="he" page with Hebrew translations: "6 שניות מתוך 12 שניות"; on lang="en": "6 seconds out of 12 seconds".
• pnpm -F vidstack test passes, with new cases for formatSpokenTime in English, Hebrew and Arabic and for an invalid language tag.

The Plyr layout is not covered here.

Review Process:

1. Open a player with the default video layout inside <html dir="rtl">.
2. Drag and click the time and volume sliders, and use the arrow keys on them.
3. Open the settings menu and its submenus, including Accessibility → Caption Styles, and toggle a switch.