[Video] Add i18n translations and navbar language selector dropdown

[Saksham-Sirohi]

Summary

Add internationalization support for the Video platform and introduce a language selector dropdown in the navbar.

Scope

• Audit Video UI for hardcoded user-facing strings.
• Externalize strings into i18n translation keys and resource files.
• Add translation support wiring for Video routes/components where missing.
• Add a navbar language selector (dropdown) in Video UI.
• Ensure selected language updates UI text in-place or after standard route reload (as per current app behavior).
• Persist selected language according to platform conventions (user profile, local storage, or existing locale mechanism).

Acceptance Criteria

• Video platform UI strings are translatable through i18n resources.
• Navbar has a working language selector dropdown.
• Changing language updates Video UI text reliably.
• Language preference persists according to current platform locale behavior.
• No regression in default language behavior.
• Missing keys degrade gracefully (fallback language).

Notes

This issue is scoped to the Video platform, including navbar language selection UX.