Array.from(it: Iterable<X> | Iterable<Y>) fails; […it] works but returns Array<X | Y>; both should return Array<X> | Array<Y>

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### 🔎 Search Terms

Array.from is currently declared as

```ts
from(iterable: Iterable | ArrayLike): T[];
```

This means that unions of distinct iterable types cannot be turned into arrays of the same type.

```ts
let foo: Iterable | Iterable = /* ... */;
let q: Array | Array = Array.from(foo); // Fails type checking, cannot find overload (2769)
```

The array splat operator has a different problem: it tries to create an array that is a union of both types.

```ts
let foo: Iterable | Iterable = /* ... */;
let q: Array | Array = [...foo]; // Fails type checking, not assignable to type (2322)
```

My instinct is that there should be some way to use variadic types here, but tbh I don't really know how.

Does this need new syntax? Or does it work within the existing type system?

### 🕗 Version & Regression Information

Since at least 4.0; prior to 4.0 it still fails but Array.from did not support taking an Iterable.

Still around in 6.0.0-dev.20251009

### ⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.9.3&ssl=19&ssc=1&pln=11&pc=1#code/PTAEHUFMBsGMHsC2lQBd5oBYoCoE8AHSAZVgCcBLA1UABWgEM8BzM+AVwDsATAGiwoBnUENANQAd0gAjQRVSQAUCEmYKsTKGYUAbpGF4OY0BoadYKdJMoL+gzAzIoz3UNEiPOofEVKVqAHSKymAAmkYI7NCuqGqcANag8ABmIjQUXrFOKBJMggBcISGgoAC0oACCbvCwDKgU8JkY7p7ehCTkVDQS2E6gnPCxGcwmZqDSTgzxxWWVoASMFmgYkAAeRJTInN3ymj4d-jSCeNsMq-wuoPaOltigAKoASgAywhK7SbGQZIIz5VWCFzSeCrZagNYbChbHaxUDcCjJZLfSDbExIAgUdxkUBIursJzCFJtXydajBVDtUAAMXgGAAvKAAJIKMgMaTuAA8glQlE4zAAfKAAD5MllszmcdiIaTffkAbmCyS4sHqjTQZDwFTIrLwVLYiAAFMlaflqbSAJSgADeihKJXcNAAjqatTquTzhoKRa6mBzJdLZaAGT68AFkvqjRaFQBfRXK1WZDXEBZ1SPwU00+CWm12tyQJ0u7W+7m8gXCypFvB+qUysiChkAbQCzeN8AAujHgiocM0PGQvIh4H02RwaF83GZmOwGMxIPxYNB1IkR3oRF4AEQAUVWDEQC3066S2PX4AcqAA5MIAHKQCTroIqADyXzI70Ec60+auqEcClc0jwUAnEHHRhiwfQUAQRBoWES5xwkIdohEAwOGxFMWDYLhuCCEogA

### 💻 Code

```ts
type Foo = Iterable | Iterable;

function tryArrayFrom(foo: Foo) {
let q: Array | Array = Array.from(foo);
}

function trySplat(foo: Foo) {
let q: Array | Array = [...foo];
}
```

### 🙁 Actual behavior

_for tryArrayFrom_
No overload matches this call.
Overload 1 of 4, '(iterable: Iterable | ArrayLike): string[]', gave the following error.
Argument of type 'Foo' is not assignable to parameter of type 'Iterable | ArrayLike'.
Type 'Iterable' is not assignable to type 'Iterable | ArrayLike'.
Type 'Iterable' is not assignable to type 'Iterable'.
The types returned by '[Symbol.iterator]().next(...)' are incompatible between these types.
Type 'IteratorResult' is not assignable to type 'IteratorResult'.
Type 'IteratorYieldResult' is not assignable to type 'IteratorResult'.
Type 'IteratorYieldResult' is not assignable to type 'IteratorYieldResult'.
Type 'number' is not assignable to type 'string'.
Overload 2 of 4, '(arrayLike: ArrayLike): (string | number)[]', gave the following error.
Argument of type 'Foo' is not assignable to parameter of type 'ArrayLike'.
Property 'length' is missing in type 'Iterable' but required in type 'ArrayLike'.

_for trySplat_
Type '(string | number)[]' is not assignable to type 'string[] | number[]'.
Type '(string | number)[]' is not assignable to type 'string[]'.
Type 'string | number' is not assignable to type 'string'.
Type 'number' is not assignable to type 'string'.

### 🙂 Expected behavior

Array.from a union of Iterables should return a union of Arrays.

### Additional information about the issue

_No response_

Beginne damit, beide Beispiele im verlinkten TypeScript Playground nachzustellen und die deklarierte Array.from-Überladung mit dem Spread-Verhalten zu vergleichen. Untersuche, wie Vereinigungen aus Iterable und Iterable inferiert werden, und ermittle anschließend, ob bestehende Mechanismen des Typsystems ohne neue Syntax Array | Array erzeugen können. Als erledigt gilt die Aufgabe, wenn beide Beispiele mit dem erwarteten Vereinigungstyp typgeprüft werden und relevante Regressionen abgedeckt sind.

Vom Indexierungsmodell aus dem Issue-Text verfasst.