Launch screen storyboard caption is not localized

## Problem

The "A PROJECT FROM THE" caption in `LaunchScreen.storyboard` is hardcoded in English. The runtime copies of this branding — the SwiftUI launch splash overlay (`LaunchSplashOverlayView`) and the first stand-by screen footer (`OHFBrandingFooter`, #5315) — are localized via `L10n.OhfBranding.caption` (`ohf_branding.caption`).

Since iOS renders the launch screen from a static snapshot, the storyboard can't use runtime localization. Non-English users briefly see the English caption on the launch screen frame before the SwiftUI splash takes over with the translated text, causing a visible mismatch during the hand-off.

## Possible directions

- Localize the storyboard text via storyboard `.strings` localization (needs verification that the launch screen snapshot cache picks up the active locale reliably, including after locale changes).
- Or remove the caption text from the storyboard and show it only from the SwiftUI splash overlay, accepting a caption-less first frame.

## Related

- #5315 (introduced the shared, localized `OHFBrandingFooter`)