tiviLux V17.3 — Stable Sports Schedule Fix

Built directly from V17.1 Mobile Sports Fix.

Changes are intentionally limited to the sports schedule backend:
- Rolls back V17.2 schedule merge changes completely.
- NFL uses ESPN only.
- NFL requests the UTC dates that overlap the requested Eastern calendar day, then filters games back to that Eastern date. This keeps late Monday/Sunday night games that cross midnight UTC.
- MLB uses MLB StatsAPI instead of TheSportsDB's limited free day feed.
- ISO timestamps are normalized as UTC before the browser converts them to local time.
- Sports falls back to XUI title-based events when an Internet schedule source is unavailable.

Unchanged from V17.1:
- Sports Hub UI/layout
- Mobile overlap/safe-area fixes
- XUI channel-title matching
- Live TV and guide
- Player
- Provider/session handling
- Favorites/search
- Startup updater