Theme Manager Upgrade
- Dashboard new Themes tab added.
- Presets: Midnight Pro, Royal Gold, Championship Red, Emerald Field, Purple Neon, Ocean Blue.
- Selected theme changes overlay scoreboard colors, glass panels, winner/next-match cards, and transparent full-screen animations.
- Settings are saved in match_state: theme_key, theme_custom_json.
- OBS Browser Source URL remains overlay.php.