add billing threshold + specific trial free credits (#11533)

In this PR : 
- set billing thresholds after subscription creation (not possible
during billing checkout)
- add specific free trial workflow credit quantities + set them in
subscription item + check them when receiving stripe alert event

closes : https://github.com/twentyhq/core-team-issues/issues/682

packages/twenty-server/src/engine/core-modules/twenty-config/config-variables.ts

@@ -509,6 +509,33 @@ export class ConfigVariables {
   @ValidateIf((env) => env.IS_BILLING_ENABLED === true)
   BILLING_FREE_TRIAL_WITHOUT_CREDIT_CARD_DURATION_IN_DAYS = 7;
 
+  @ConfigVariablesMetadata({
+    group: ConfigVariablesGroup.BillingConfig,
+    description: 'Amount of money in cents to trigger a billing threshold',
+  })
+  @IsNumber()
+  @CastToPositiveNumber()
+  @ValidateIf((env) => env.IS_BILLING_ENABLED === true)
+  BILLING_SUBSCRIPTION_THRESHOLD_AMOUNT = 10000;
+
+  @ConfigVariablesMetadata({
+    group: ConfigVariablesGroup.BillingConfig,
+    description: 'Amount of credits for the free trial without credit card',
+  })
+  @IsNumber()
+  @CastToPositiveNumber()
+  @ValidateIf((env) => env.IS_BILLING_ENABLED === true)
+  BILLING_FREE_WORKFLOW_CREDITS_FOR_TRIAL_PERIOD_WITHOUT_CREDIT_CARD = 5000;
+
+  @ConfigVariablesMetadata({
+    group: ConfigVariablesGroup.BillingConfig,
+    description: 'Amount of credits for the free trial with credit card',
+  })
+  @IsNumber()
+  @CastToPositiveNumber()
+  @ValidateIf((env) => env.IS_BILLING_ENABLED === true)
+  BILLING_FREE_WORKFLOW_CREDITS_FOR_TRIAL_PERIOD_WITH_CREDIT_CARD = 10000;
+
   @ConfigVariablesMetadata({
     group: ConfigVariablesGroup.BillingConfig,
     isSensitive: true,