fix(settings): make codec priority reorderable by keyboard and touch

[czoli1976]

What is this PR doing?

Makes the codec priority list in Settings → Video reorderable by keyboard and on touch.

The list was HTML5 drag-and-drop only — no key handlers, no ARIA, no touch path:

// AdvancedSettingsCodecPriorityField.tsx (before)
<li
  key={codec}
  draggable
  onDragStart={…}
  onDragEnd={handleDragEnd}
  onDragOver={…}
  onDrop={…}
>

Two consequences:

• Keyboard users cannot reorder the codecs at all. There is no focusable control and no key
  handler anywhere in the field — a WCAG 2.1.1 Keyboard (Level A) failure.
• The control is inert on touch. HTML5 drag events are not synthesised from touch input, so on
  phones and tablets — where this dialog renders full-screen — the setting can be read but never
  changed.

This adds a Move up / Move down button to each row, disabled at the ends of the list, each
with a translated aria-label naming the codec it acts on ("Move VP9 up"). Both delegate to the
existing pure reorderCodecPriority helper, so ordering behaviour is unchanged and there is no
second implementation to keep in sync:

const moveCodec = (codec: AdvancedSettingsVideoCodec, offset: -1 | 1) => {
  const targetCodec = codecPriority[codecPriority.indexOf(codec) + offset];

  if (!targetCodec) return;

  setCodecPriority(reorderCodecPriority({ codecPriority, draggedCodec: codec, targetCodec }));
};

Drag-and-drop is deliberately untouched, so mouse users lose nothing.

One piece of scope that is not accessibility. The field's data-testids were hardcoded, so the
component could only ever be rendered once per page. This adds an idPrefix prop (defaulting to
today's value, so nothing changes) to make a second instance addressable. That is groundwork for a
screen-share codec section; it is included here because it touches the same lines as the testids
above and would otherwise conflict.

New keys land in all five locale files in this commit, so localeParity.spec.ts stays green.

How should this be manually tested?

1. Settings → Video → Codec → Manual to reveal the priority list.
2. Keyboard only: Tab to a Move up / Move down button and activate it with Enter or Space. The
   codec should change position and the numbering update. On develop there is nothing to Tab to.
3. Touch: on a phone, tablet, or device emulation, tap the buttons. On develop dragging does
   nothing at all.
4. Mouse: drag-and-drop should behave exactly as before.
5. The first row's Move up and the last row's Move down are disabled.

Verified manually in the browser across all four paths.

Known and deliberately out of scope

Flagged so they read as decisions rather than oversights:

• No status announcement after a move. The visible order and the position numbers change, but
  nothing is announced to a screen reader (WCAG 4.1.3 Status Messages, AA). Worth adding an
  aria-live region, but it is a separate concern from the Level A keyboard failure this fixes.
• Buttons are 28px. Above the 24px minimum of WCAG 2.5.8 Target Size (Minimum, AA), below the
  44px of 2.5.5 (AAA). Sized to match the existing row furniture rather than introduce a
  one-off.

What are the relevant tickets?

A maintainer will add this ticket number.

Resolves VIDSOL-

Checklist

[x] Branch is based on develop (not main).
[ ] Resolves a Known Issue.
[ ] If yes, did you remove the item from the docs/KNOWN_ISSUES.md?
[x] Resolves an item reported in Issues.
If yes, which issue? #739

[vonage-ai-assistant]

AI Adoption Report

	Lines	%
AI-generated	0	0%
Human	0	100%
Untracked	175	—
Total	175

Per-commit breakdown (3 commits)

Commit	Message	Added	AI	Human	AI %
3102041	chore(i18n): move the Video section labels out of this PR	0	—	—	untracked
3e76d3a	fix(settings): keep the move buttons focusable at the ends o	53	—	—	untracked
6a7b280	feat(settings): make codec priority reorderable by keyboard	122	—	—	untracked

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• 3102041 chore(i18n): move the Video section labels out of this PR
• 3e76d3a fix(settings): keep the move buttons focusable at the ends o
• 6a7b280 feat(settings): make codec priority reorderable by keyboard

---

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud