fix: standardize billing order status values and apply full-day expiry grace rule

- home_handling_functions.php: display expiration as Y-m-d only (not Y-m-d H:i);
  apply full-day grace by comparing date-only (midnight) in PHP so a server
  expiring on today's date remains Active the entire day
- cron-shop.php Step B & C: change server_expiration_date comparisons from
  < DATE_SUB(NOW(), ...) to DATE(server_expiration_date) < DATE_SUB(CURDATE(), ...)
  ensuring the full expiration day is honoured
- user_games/check_expire.php: change all three expiration queries from
  <= time() to < strtotime(date('Y-m-d')) (today-midnight) for full-day grace
- billing/test_integration.php: replace status='paid' (old order status) with
  status IN ('Active','paid') for backward compat during migration
- user_games/billing_integration.php: clarify comment that billing_invoices.status
  uses the payment lifecycle ('paid'/'unpaid'/'due'), separate from billing_orders.status
- Add modules/billing/sql/normalize_billing_order_status.sql migration script
  to convert installed->Active, paid->Active, suspended->Expired in existing rows
- Update CHANGELOG.md

Agent-Logs-Url: https://github.com/GameServerPanel/GSP/sessions/439845e0-926e-4b49-9cd0-810457b73c12

Co-authored-by: iaretechnician <2749183+iaretechnician@users.noreply.github.com>

modules/billing/cron-shop.php

@@ -215,7 +215,7 @@ $past_due = $db->resultQuery("
     WHERE sh.billing_enabled      = 1
       AND sh.billing_status       = 'Invoiced'
       AND sh.server_expiration_date IS NOT NULL
-      AND sh.server_expiration_date < DATE_SUB(NOW(), INTERVAL {$grace_days} DAY)
+      AND DATE(sh.server_expiration_date) < DATE_SUB(CURDATE(), INTERVAL {$grace_days} DAY)
       AND (
           sh.last_invoice_id IS NULL
           OR EXISTS (
@@ -284,7 +284,7 @@ $to_delete = $db->resultQuery("
     WHERE sh.billing_enabled       = 1
       AND sh.billing_status        = 'Expired'
       AND sh.server_expiration_date IS NOT NULL
-      AND sh.server_expiration_date < DATE_SUB(NOW(), INTERVAL {$delete_after_days} DAY)
+      AND DATE(sh.server_expiration_date) < DATE_SUB(CURDATE(), INTERVAL {$delete_after_days} DAY)
     ORDER BY sh.home_id ASC
 ");