ICYLAB OS Billing Enforcement Hotfix v6.10

Patch-only package. Extract over the production app root.
Does NOT include core/private_config.php, credentials, tokens, storage files, or SQL data.

New files:
- services/billing/BillingRuntimeGate.php
- scripts/billing_runtime_gate_diagnostic_v6_10.php

All other files replace existing application files.
