fix(evh): rename Transport.bind + null AwsLambdaContext

[adrians5j]

What changed

Three small follow-up cleanups on the event-handler layer, on top of the Transport refactor that landed in #5359. No behavior change for end users or API consumers.

• Rename Transport.extract → Transport.bind. The method name read backwards — it pushes raw platform args into the request container, it doesn't pull anything out. bind describes what it does. Renamed across the Transport interface, noopTransport, the createHandler call site, and awsLambdaTransport.
• Remove the unused Function URL transport. FunctionUrlEventType and FunctionUrlTranslator were scaffolded but never wired into any feature, handler, or template — only their own tests referenced them. Removed both, their index exports, and the covering tests.
• Always register AwsLambdaContext (null object). Per review feedback: instead of registering AwsLambdaContext only when a Lambda context is present (which forces consumers to handle a missing registration), always register one. It's now an IAwsLambdaContext with isSet() / get(); the transport binds a real value when a context exists and a NullAwsLambdaContext (isSet() === false) when it doesn't, so consumers can resolve it unconditionally and branch on isSet().

Changelog

Title line: Tidy up the event handler transport layer

Body: Internal cleanups to the request-handling layer: clearer naming, removal of an unused code path that was never hooked up, and a more robust way of exposing the AWS Lambda context so downstream code never has to guard against it being absent. No change to how applications behave.

Squash Merge Commit

refactor(event-handler): tidy transport layer (bind, null context, cleanup) (#5360)

refactor(event-handler): rename Transport.bind + null AwsLambdaContext (#5360)