Scoreboard Live Update Fix

Problem:
Match started but scoreboard did not update.

Root cause:
The real API is api/get_score.php and its response is nested:
{
  ok: true,
  score: {...},
  events: [...]
}

The overlay JS expected flat data.

Fixed:
- overlay_scoreboard_main_only.js now loads api/get_score.php first.
- It flattens response.score into overlay fields.
- It maps events[] into THIS OVER ball timeline.
- Compatibility APIs live_score.php / overlay_data.php / score.php proxy to get_score.php.
- Update interval reduced to 700ms.

Test:
http://localhost/point/api/get_score.php
http://localhost/point/overlay.php