Changes to Create a session — starts provisioning by default; optionally defer until the first turn [write]

added the new optional header request parameter Idempotency-Key

added the new optional request property browserProfile

added the new optional request property initial_events/items/interaction_mode

added the new optional request property local_mirror

added the new optional request property mcp_servers

added the new optional request property payer

added the new optional request property subscriptionApiFallback

added the optional property error/request_id to the response with the default status

added the optional property session/attachments to the response with the 201 status

added the optional property session/browserLoginsSavedAt to the response with the 201 status

added the optional property session/browserProfile to the response with the 201 status

added the optional property session/budget/consumed_cost/amount_usd to the response with the 201 status

added the optional property session/budget/consumed_cost/unit to the response with the 201 status

added the optional property session/budget/max_list_cost/amount_usd to the response with the 201 status

added the optional property session/budget/max_list_cost/unit to the response with the 201 status

added the optional property session/contextFiles to the response with the 201 status

added the optional property session/harnessVersion to the response with the 201 status

added the optional property session/hostedBySeller to the response with the 201 status

added the optional property session/parentRelation to the response with the 201 status

added the optional property session/parentSessionId to the response with the 201 status

added the optional property session/payer to the response with the 201 status

added the optional property session/provisioningStage to the response with the 201 status

added the optional property session/subscriptionApiFallback to the response with the 201 status

the response property error became required for the status default

the response property error/code became required for the status default

the response property error/message became required for the status default

the response property session/budget/consumed_cost/amount became required for the status 201

the response property session/budget/consumed_cost/currency became required for the status 201

the response property session/budget/max_list_cost/amount became required for the status 201

the response property session/budget/max_list_cost/currency became required for the status 201