Game Management: soft-delete, slug reuse, new game form fix, master-admin gating

- DB: added is_deleted, deleted_at columns to platforms table
- Soft delete: archive button moves games to archived section instead of hard delete
- Archived section: master admin can restore (reactivates) or permanently delete
- Slug reuse: creating a game with an archived slug reactivates the old record
- New game form: master admin always sees add form + agent info; other admins hidden
- Edit: non-master admins have form card revealed on edit
- Delete/Add buttons: only visible to master admin
- api/platforms.php: public and admin_list queries exclude archived games
- api/admin.php: platforms_archived, platforms_restore, platforms_purge actions added

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/platforms.php

@@ -12,7 +12,7 @@ switch ($action) {
 
     // ── Public: active platforms for player app ───────────
     case 'list':
-        $stmt = db()->query("SELECT slug,name,player_url,color,icon_path FROM platforms WHERE is_active=1 ORDER BY sort_order ASC, id ASC");
+        $stmt = db()->query("SELECT slug,name,player_url,color,icon_path FROM platforms WHERE is_active=1 AND is_deleted=0 ORDER BY sort_order ASC, id ASC");
         $rows = $stmt->fetchAll();
         // Normalize to match old CFG format
         $out = array_map(fn($r) => [
@@ -27,7 +27,7 @@ switch ($action) {
     // ── Admin: full list including agent fields and inactive ─
     case 'admin_list':
         if (!$isAdmin) { echo json_encode(['success'=>false,'error'=>'Forbidden']); exit; }
-        $rows = db()->query("SELECT * FROM platforms ORDER BY sort_order ASC, id ASC")->fetchAll();
+        $rows = db()->query("SELECT * FROM platforms WHERE is_deleted=0 ORDER BY sort_order ASC, id ASC")->fetchAll();
         echo json_encode(['success'=>true, 'platforms'=>$rows]);
         break;