Director Overlay & Graphics Updated

Requested changes:
- Removed old Overlay/Graphics controls.
- Removed Show Playing XI.
- Added only 3 buttons:
  1. Show Toss
  2. Show Next Match
  3. Hide Graphic
- Buttons open popup.
- Popup loads fixture matches from tournament_matches table.
- Toss uses selected fixture match and Team A/Team B toss winner selector.
- Next Match uses selected fixture match and optional Time/Venue.

New files:
- api/prematch_fixture_list.php
- api/prematch_match_get.php
- assets/css/director_overlay_graphics_popup.css
- assets/js/director_overlay_graphics_popup.js

Fixed:
- Match list query now checks actual DB columns first, so missing stage/venue/match_time columns won't break.