Arithmetic operations on type-parameters subtyping `bigint` are incorrectly inferred to have type `number`

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### 🔎 Search Terms

bigint, operator, arithmetic, number, subtype, extend, generic, type parameter, incorrect, inference, inferred type, operation, 2365, TS2365

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about arithmetic/bigints/etc

### ⏯ Playground Link

https://www.typescriptlang.org/play/?target=99&ts=5.8.2#code/GYVwdgxgLglg9mABAIxlAzgUygSTFTAJy2gB4AhNdRTADwLABNrUBzGfAPgAoBDALkSUMAGhSDh6AJSCwIALbIiiAN4AoRJsQB6bYg4FimaPCQxqHYEUKZGiKHEQALXgDdM9gJ4AHDwAM5RSI-REJeKCdlCN4kPzYDPw0tCAR0KH18IhJYBEQAXkReRAAyFABuNSTNXUQAVgA6AA56gCZQzG84QgxEMEcoHw9rLpEqnT1kEHSiwnBYeSHCQi7EOAgIEGJ+MZqAbQBRACVDgF1BAGEYvvT5GFohGFY8aaZViKjB9DEQLBpabwANjAIGhECkwO5iKZqGMbFBNmZMkYTLkALSIACMFQAvpVweg4ADMPUAXBWNxUBhsM8ssYoNwAOxgMS1MBSKQVIA

### 💻 Code

```ts
function bitsetIntersect(a: Bits, b: Bits): number {
// intersection is inferred to have type `number` rather than `bigint`
const intersection = a & b;

// 5.8.2 reports no type error,
// but a runtime error occurs:
// [ERR]: Cannot mix BigInt and other types, use explicit conversions
return intersection - 1;
}

console.log(bitsetIntersect(7n, 5n));
```

### 🙁 Actual behavior

`intersection` is inferred to have type `number`. As a result, no type errors are reported.

When run, the code encounters a TypeError because `intersection - 1` attempts to perform arithmetic on a bigint and a number:

> [ERR]: Cannot mix BigInt and other types, use explicit conversions

### 🙂 Expected behavior

`intersection` should be inferred to have type `bigint`.

Thus the operation `intersection - 1` should report a type error:

> Operator '-' cannot be applied to types 'bigint' and 'number'. (2365)

### Additional information about the issue

This issue is most likely to be hit when _branding_ `bigint`, but it could also appear in other situations, such as using subtypes which are unions of literals.

---

I found some issues that are similar, but have a different scope. These issues were closed as intended, but in these issues, larger type bounds which include `bigint` _but also include `number`_ (such as `any` or `bigint | number`) are used:

* #39569
* #41741
* #42125
* #49558
* #60914

Beginne damit, die verlinkte Playground-Reproduktion auszuführen und den abgeleiteten Typ sowie das TS2365-Verhalten zu bestätigen. Verfolge dann die Logik des TypeScript-Typprüfers für arithmetische Operationen mit generischen Typparametern, die durch bigint eingeschränkt sind, und füge einen Regressionstest für das Beispiel hinzu oder finde einen solchen. Fertig ist die Aufgabe, wenn die Schnittmenge als bigint behandelt wird und das Subtrahieren einer number den erwarteten Fehler erzeugt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.