Tutorials: Rename Tutorial.run to start

[alex-aprm]

The failure

Tutorials is one of four packages still failing to build in the nightly:

libraries/tutorials/src/tutorial.ts(127,9)
TS2416: Property 'run' in type 'Tutorial' is not assignable to the
        same property in base type 'Widget<any>'

The u2 refactor added a scope helper to the Component base:

// js-api/src/u2core/component.ts
run<T>(fn: () => T): T { return Scope.runWith(this.scope, fn); }

Tutorial extends DG.Widget, and Widget → Control → Component, so it now inherits run(fn) — which its own async run(): Promise<void> no longer matches.

Why renaming is the only option here

No signature satisfies both. A subclass may drop parameters, but it cannot return Promise<void> where the base returns T. Unlike the name accessor case (#4005), there is no override shape that works — the member has to be called something else.

Why this side, and why start

Renaming the u2 helper would be the alternative, but it has ~38 call sites across libraries/u2, not all of which are Component.run, in a library under active development. Renaming Tutorial.run is far smaller and contained:

• start is free on Component, Control and Widget — checked, so this does not trade one collision for another
• subclasses are untouched: they implement the protected _run() hook, which does not collide; only the base declares the public entry point
• 3 call sites, and one of them sits directly under the 'Start' button that launches the next tutorial, so the name reads correctly

Verification

Compiled tutorial.ts against the current js-api sources:

	TS2416
before (origin/master)	1 — tutorial.ts(127,9)
after	0

No new errors introduced.

Compute and DevTools fail on the same collision via FunctionView.run in libraries/compute-utils; that is a separate change and not included here.

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