feat: sync rcat data (#13628)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* RevenueCat support: public webhook endpoint, webhook handler/service,
nightly reconciliation and per-user sync; subscriptions now expose
provider and iapStore; new user-facing error for App Store/Play-managed
subscriptions.
* **Chores**
* Multi-provider subscription schema (Provider, IapStore); Stripe
credentials moved into payment.stripe (top-level apiKey/webhookKey
deprecated); new payment.revenuecat config and defaults added.
* **Tests**
  * Comprehensive RevenueCat integration test suite and snapshots.
* **Documentation**
  * Admin config descriptions updated with deprecation guidance.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/payment/manager/user.ts

@@ -9,6 +9,7 @@ import {
   EventBus,
   InternalServerError,
   InvalidCheckoutParameters,
+  ManagedByAppStoreOrPlay,
   Mutex,
   OnEvent,
   SubscriptionAlreadyExists,
@@ -103,6 +104,14 @@ export class UserSubscriptionManager extends SubscriptionManager {
       throw new InvalidCheckoutParameters();
     }
 
+    const active = await this.getActiveSubscription({
+      plan: lookupKey.plan,
+      userId: user.id,
+    });
+    if (active?.provider === 'revenuecat') {
+      throw new ManagedByAppStoreOrPlay();
+    }
+
     const subscription = await this.getSubscription({
       plan: lookupKey.plan,
       userId: user.id,
@@ -256,7 +265,7 @@ export class UserSubscriptionManager extends SubscriptionManager {
       ]),
       create: {
         targetId: userId,
-        ...subscriptionData,
+        ...omit(subscriptionData, ['provider', 'iapStore']),
       },
     });
   }