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/message-queue/jobs.module.ts

@@ -15,6 +15,7 @@ import { StripeModule } from 'src/engine/core-modules/billing/stripe/stripe.modu
 import { EmailSenderJob } from 'src/engine/core-modules/email/email-sender.job';
 import { EmailModule } from 'src/engine/core-modules/email/email.module';
 import { EnterpriseModule } from 'src/engine/core-modules/enterprise/enterprise.module';
+import { FeatureFlagModule } from 'src/engine/core-modules/feature-flag/feature-flag.module';
 import { GenerateSdkClientJob } from 'src/engine/core-modules/sdk-client/jobs/generate-sdk-client.job';
 import { SdkClientModule } from 'src/engine/core-modules/sdk-client/sdk-client.module';
 import { UserWorkspaceModule } from 'src/engine/core-modules/user-workspace/user-workspace.module';
@@ -65,6 +66,7 @@ import { WorkflowModule } from 'src/modules/workflow/workflow.module';
     CalendarEventParticipantManagerModule,
     TimelineActivityModule,
     StripeModule,
+    FeatureFlagModule,
     AutoCompaniesAndContactsCreationJobModule,
     TimelineJobModule,
     WebhookJobModule,