Billing - Migrate from Stripe metering (#20298)

**Overall strategy**
**1. Introduce “Billing V2” behind a workspace flag**
Gate the new model with FeatureFlagKey.IS_BILLING_V2_ENABLED so existing
workspaces stay on the old behavior until they’re migrated or explicitly
on V2.

**2. Replace workflow metered SKUs with a resource-credit product**
Conceptually, billable “workflow execution” usage is not the primary
subscription line item anymore. Add a RESOURCE_CREDIT product (and keep
WORKFLOW_NODE_EXECUTION as deprecated for the transition). Usage and
limits are expressed through credit buckets (e.g. price metadata like
credit_amount), so one product can represent pooled credits instead of a
narrow workflow-only meter.

**3. Migrate subscriptions in two layers**
Schema/catalog: persist extra price metadata (instance upgrade) so the
server knows credit amounts and can match Stripe prices to the new
model.
Per workspace: the registered workspace command
upgrade:2-2:migrate-to-billing-v2 finds subscriptions that still have
WORKFLOW_NODE_EXECUTION, swaps those items to the right RESOURCE_CREDIT
prices (using existing Stripe schedule +
BillingSubscriptionUpdateService stack), then treats the workspace as V2
(flag). Workspaces without that legacy item or without a subscription
are skipped.

**4. Unify subscription lifecycle + usage on the server**

**5. Refresh the product surface in Settings**

Test : 

- [x] Subscribe v1 +  Update subscribe + Migrate
- [x]  Subscribe v2 + Update subscribe

packages/twenty-server/src/engine/core-modules/logic-function/logic-function-executor/logic-function-executor.service.ts

@@ -351,6 +351,23 @@ export class LogicFunctionExecutorService {
         functionName: flatLogicFunction.name,
       });
 
+    let periodStart: Date | undefined;
+
+    if (this.billingService.isBillingEnabled()) {
+      const {
+        billingSubscription: { currentPeriodStart },
+      } = await this.workspaceCacheService.getOrRecompute(workspaceId, [
+        'billingSubscription',
+      ]);
+
+      periodStart = currentPeriodStart;
+
+      await this.billingUsageService.decrementAvailableCredits({
+        workspaceId,
+        usedCredits: 100,
+      });
+    }
+
     this.workspaceEventEmitter.emitCustomBatchEvent<UsageEvent>(
       USAGE_RECORDED,
       [
@@ -361,16 +378,10 @@ export class LogicFunctionExecutorService {
           quantity: 1,
           unit: UsageUnit.INVOCATION,
           resourceId: flatLogicFunction.id,
+          periodStart,
         },
       ],
       workspaceId,
     );
-
-    if (this.billingService.isBillingEnabled()) {
-      await this.billingUsageService.decrementAvailableCredits({
-        workspaceId,
-        usedCredits: 100,
-      });
-    }
   }
 }