Feature: Wire I18nController into UI Elements and Move Error Dialog Defaults to Core

[sampotts]

Note

Triage estimate — cycle priority and story points were assigned during an AI-assisted planning pass and are rough first guesses. Confirm or adjust when you pick this up.

Wire I18nController into HTML UI elements and move error dialog defaults to core.

Epic: #222
PR: #1591 (stack PR 3/5, combined with HTML layer)

Deliverables

• MediaButtonElement and controls use I18nController for auto-forwarded aria labels
• Error dialog i18n helpers in core; HTML element consumes translated copy
• Tooltip and time/volume slider translated value text

Depends on

#1589 (core UI keys + error dialog i18n), #1590 (loadLocale)

[github-actions]

Planning Recommendations

Epic: Already linked to #222 (Feature: Internationalization) — correct.

Blocked by: #1363, #1365, #1366 — correctly called out. This issue cannot start until all three unblock (core i18n types, HTML i18n layer, and opaque translation keys in core UI components are all in-flight).

Milestone: 26.3 [GA] — recommend targeting this milestone, as it finalizes the "skins are i18n-unaware" goal that appears to be a GA-readiness requirement for the i18n epic.

Priority: P1 — this closes the last hardcoded-English gap in the HTML layer and is a direct prerequisite for shipping a complete i18n story.

Related issues to plan alongside:

• Feature: Update HTML Skin Templates with <media-text> #1370 (Feature: Update HTML Skin Templates with <media-text>) — skin template updates will likely need to be coordinated with the error dialog copy removal here to avoid conflicts in skin.ts / audio/skin.ts / minimal-skin.ts.

Label note: Added a11y — the aria-label forwarding via I18nController is accessibility-critical work, not just i18n plumbing.