Add ticket_state_id to convert conversation to ticket request schema (#440)

The public API convert endpoint now accepts an optional ticket_state_id
parameter to set the initial ticket state during conversion, matching
the existing update ticket endpoint pattern.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: junaid-zaidi-intercom

descriptions/0/api.intercom.io.yaml

@@ -21639,6 +21639,10 @@ components:
           description: The ID of the type of ticket you want to convert the conversation
             to
           example: '1234'
+        ticket_state_id:
+          type: string
+          description: The ID of the ticket state associated with the ticket type.
+          example: '123'
         attributes:
           "$ref": "#/components/schemas/ticket_request_custom_attributes"
       required: