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/sql/normalize_billing_order_status.sql

@@ -0,0 +1,37 @@
+-- normalize_billing_order_status.sql
+-- ============================================================
+-- Migrate legacy billing_orders.status values to the canonical
+-- three-value lifecycle used by GSP billing:
+--
+--   Active   – server is provisioned and current
+--   Invoiced – renewal invoice generated; payment due
+--   Expired  – invoice unpaid past due date; server pending deletion
+--
+-- Old values and their mappings:
+--   installed  -> Active   (was written by old provisioner)
+--   paid       -> Active   (was written after PayPal capture, before provisioning)
+--   suspended  -> Expired  (was written by old cron when overdue)
+--
+-- Run this ONCE against the panel database after deploying the updated
+-- cron-shop.php and application code.  It is safe to re-run (idempotent).
+-- ============================================================
+
+-- Map old 'installed' to 'Active'
+UPDATE `gsp_billing_orders`
+SET    `status` = 'Active'
+WHERE  `status` = 'installed';
+
+-- Map old 'paid' to 'Active'
+-- (Orders that were paid but not yet provisioned should be provisioned
+--  via home.php?m=billing&p=provision_servers after this migration.)
+UPDATE `gsp_billing_orders`
+SET    `status` = 'Active'
+WHERE  `status` = 'paid';
+
+-- Map old 'suspended' to 'Expired'
+UPDATE `gsp_billing_orders`
+SET    `status` = 'Expired'
+WHERE  `status` = 'suspended';
+
+-- Optional: verify counts after migration
+-- SELECT status, COUNT(*) AS count FROM gsp_billing_orders GROUP BY status ORDER BY count DESC;