Update the TypeScript SDK docs for Dags declared in TypeScript

[jason810496]

Reorganizes the TypeScript SDK docs around its two ways of use, now that Dag definition in TypeScript is on main.

What

• typescript.rst covers Dag definition first, then a Python Dag with stub TaskHandler: task inputs, task ids, options, order-only dependencies, task groups, dag.if, dag.switch, triggerDagRun, and deploying a bundle into a Dag bundle.
• The language SDK overview is split the same way, and its table shows which SDKs support Dag definition.
• The README, the API reference landing page and the example README follow the same shape.

import { Bundle, Dag } from "apache-airflow-ts-sdk";

const dag = new Dag("ts_etl", { schedule: "@daily", queue: "typescript" });

const extract = dag.task("extract", async (): Promise<number> => 42);
const load = dag.task("load", async ({ rows }: { rows: number }) => {});

load({ rows: extract() });

await new Bundle(dag).serve();

The README's compatibility matrix is generated from capabilities.yaml and is left alone.

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Was generative AI tooling used to co-author this PR?

• Yes, with help of Claude Code Opus 5.5 following the guidelines

[pierrejeambrun]

Thanks. A few suggestions / questions

PR description mentions PR 73848 which doesn't exists, probably referring to #73844.

[pierrejeambrun]

Meant to approve feel free to merge when those small comments are resolved.

[jason810496]

Thanks for the review, I just address all the review comments.