fix(mothership): parse each checkpoint control request on its own and declare accepted kinds - #9086

Summary

• The outbound Mothership receiver parsed each poll batch strictly, so one control kind this build didn't know threw for the whole batch: nothing in it was answered and the worker waited out every request's timeout
• Each request now parses on its own: an unknown kind is answered 501 sim_control_unsupported, a malformed one 400, a request without a readable id is dropped and logged, and its batch-mates always run
• Every poll declares accepts: the kinds this build's generated contract parses, so the worker can stop sending kinds a receiver can't handle
• Disconnect log now says which phase failed (poll / parse / reply)
• generated/sim-transport.ts synced from simstudioai/mothership#699

Release order

• Lands with simstudioai/mothership#699 (contracts only). Safe alone: current workers ignore the extra accepts field
• The worker-side gate ships after this Sim release

Type of Change

• Bug fix

Testing

• receiver.test.ts: a batch with an unknown kind, a malformed input, and a request with no kind alongside a valid one: valid one executes, the others get 501/400, no reconnect; polls declare exactly the contract's kinds; unreadable requests are dropped without a reply (all fail before the change)
• control.test.ts unchanged and passing

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)