Introducing the TypeScript Task SDK (initial PR - 66289)

[Shivam Rastogi]

Hi everyone,

Following the Go SDK pattern adapted for Node's runtime, I've opened an
initial PR for a Node.js / TypeScript Task SDK.

*PR Link:* https://github.com/apache/airflow/pull/66289

I would appreciate feedback from reviewers with node experience on the
package layout, public APIs, and runtime design.


*The scope of this PR is minimal:*

   - Two public APIs: registerTask + startWorker.
   -

   Typed Edge and Execution API clients with retry, heartbeat circuit
   breaker, and SIGTERM drain.
   -

   Workload→execution token swap (recently introduced in PR #60108).
   -

   Unit and local integration tests included.

*Deferred to follow-ups:* XCom / Variables / Connections, log forwarding,
and Coordinator integration.

I'm committed to maintaining this SDK long term and shipping the follow-up
scope.

Regards,

Shivam Rastogi