## Summary
Fixes a bug where `BillingUsageService.billUsage()` only sent the first
event from the `billingEvents` array to Stripe, silently ignoring all
subsequent events.
## Bug Description
The `billUsage()` method accepts an array of `BillingUsageEvent[]` but
was only processing `billingEvents[0]`, causing:
- Customers to be undercharged for their usage
- Revenue loss due to unbilled events
- Incorrect usage tracking
## Fix
Changed the implementation to use `Promise.all()` to send all events in
the array concurrently to Stripe.
## Before
```typescript
await this.stripeBillingMeterEventService.sendBillingMeterEvent({
eventName: billingEvents[0].eventName, // Only first event
value: billingEvents[0].value,
stripeCustomerId: workspaceStripeCustomer.stripeCustomerId,
dimensions: billingEvents[0].dimensions,
});
```
## After
```typescript
await Promise.all(
billingEvents.map((event) =>
this.stripeBillingMeterEventService.sendBillingMeterEvent({
eventName: event.eventName,
value: event.value,
stripeCustomerId: workspaceStripeCustomer.stripeCustomerId,
dimensions: event.dimensions,
}),
),
);
```
