[backport cloud/1.38] feat: wire renewal_date from cloud billing status (#8755)

Backport of #8754 to `cloud/1.38`

Automatically created by backport workflow.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8755-backport-cloud-1-38-feat-wire-renewal_date-from-cloud-billing-status-3026d73d3650818e8281cf0778dc0137)
by [Unito](https://www.unito.io)

Co-authored-by: Hunter <huntcsg@users.noreply.github.com>

src/composables/billing/useWorkspaceBilling.ts

@@ -47,7 +47,7 @@ export function useWorkspaceBilling(): BillingState & BillingActions {
       tier: status.subscription_tier ?? null,
       duration: status.subscription_duration ?? null,
       planSlug: status.plan_slug ?? null,
-      renewalDate: null, // Workspace billing uses cancel_at for end date
+      renewalDate: status.renewal_date ?? null,
       endDate: status.cancel_at ?? null,
       isCancelled: status.subscription_status === 'canceled',
       hasFunds: status.has_funds

src/platform/workspace/api/workspaceApi.ts

@@ -211,6 +211,7 @@ export interface BillingStatusResponse {
   billing_status?: BillingStatus
   has_funds: boolean
   cancel_at?: string
+  renewal_date?: string
 }
 
 export interface BillingBalanceResponse {