Description

• Add subscriptionLimits property to the Call schema in openapi.json
• The SubscriptionLimits schema already exists and is referenced by CallBatchResponse, but was missing from the Call schema
• The live API (POST /call) returns subscriptionLimits in the response, and this is documented in fern/calls/call-concurrency.mdx, but the OpenAPI spec Call schema did not include it
• This causes all auto-generated SDKs (C#, Python, TypeScript, etc.) to be missing the subscriptionLimits field on the Call object
• Once merged and SDKs are regenerated, the field will be available in all Vapi SDKs

Fixes PRO-1773

Testing Steps

• Run fern check -- passes with 0 errors (5 pre-existing warnings unrelated to this change)
• Validated JSON syntax is correct
• Verified $ref points to existing SubscriptionLimits schema (with concurrencyBlocked, concurrencyLimit, remainingConcurrentCalls properties)
• Run the app locally using fern docs dev or navigate to preview deployment
• Ensure that the changed pages and code snippets work