Enhance API with OIDC support, including login and callback endpoints. Update environment variables for OIDC configuration in .env.example. Add new features to the catalog service for listing software families, Minecraft versions, and deployment regions. Implement server management actions such as kill, delete, and update in the servers module. Integrate feature flags for maintenance mode in server operations. Update pnpm-lock.yaml with new dependencies and versions.

docs/integrations/whmcs/addons.md

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+# WHMCS addon products
+
+Bill optional GameCloud features as WHMCS addon products linked to the main Minecraft service.
+
+## Supported addon types
+
+| WHMCS addon | GameCloud feature | Module action |
+|-------------|-------------------|---------------|
+| Extra backup retention | Extended backup slots | Usage / plan metadata sync |
+| Dedicated IP (future) | Reserved port/IP on node | Manual / Phase 10 |
+| Priority support | No technical change | Billing only |
+
+Technical addons call GameCloud APIs during `CreateAccount` / `TerminateAccount` on the addon service or via usage records — see [usage billing](../usage-billing.md).
+
+## Setup
+
+**Setup → Products/Services → Product Addons → Create New Addon**
+
+1. Assign to Minecraft parent products
+2. Module: **HexaHost GameCloud** (if addon provisioning implemented) or **None** for pure billing markers
+3. Map addon ID in GameCloud addon module **Mappings** (addon tab) when available
+
+## Linking to parent service
+
+GameCloud correlates via:
+
+- `externalServiceId` — parent WHMCS service ID
+- `externalAddonId` — addon service ID (usage export)
+
+Ensure parent service is provisioned before addon activation.
+
+## Lifecycle
+
+| WHMCS event | Expected behavior |
+|-------------|-------------------|
+| Addon ordered | Enable feature flag on server |
+| Addon suspended | Disable feature; do not delete data |
+| Addon terminated | Revert limits; purge addon-specific data |
+
+## Metered addons
+
+For usage-based billing (playtime, storage overage):
+
+1. GameCloud worker aggregates usage
+2. WHMCS polls via addon module or server module metric export
+3. WHMCS generates invoices — [usage billing](../usage-billing.md)
+
+## Reconciliation
+
+Orphaned addons (parent terminated, addon active) appear in **Reconciliation** dashboard. Run dry-run before live fix.
+
+## Related
+
+- [Products](products.md)
+- [Usage billing](../usage-billing.md)
+- [Reconciliation](../reconciliation.md)