Completion does not work for generic type extending tuple or array of all partial type

まだ誰も着手していません。

### Extension Version

0.20251202.1

### VS Code Version

1.103.2

### Operating system Version

Linux Mint 22.2 Zara

### Steps to reproduce

1. Paste the following code into VS Code.
2. In each example, type com... and check whether it is auto-completed.

### Issue

```ts
// All partial type works

type AllPartialObject = {
component?: string
}

declare function extendTheme1(
extensions: Extensions
): void

extendTheme1([
{
/* Can autocomplete `component` here */
},
])

// But all partial type with mapped types doesn't work

declare function extendTheme2<
Extensions extends [AllPartialObject & Record],
>(extensions: Extensions): void

extendTheme2([
{
/* Can't autocomplete `component` here */
},
])

// with required field works

type PartialWithRequiredObject = {
component?: string
requiredField: string
}

declare function extendTheme3<
Extensions extends [PartialWithRequiredObject & Record],
>(extensions: Extensions): void

extendTheme3([
{
/* Can autocomplete `component` here */
},
])

// but with required field and complete required field doesn't work

extendTheme3([
{
requiredField: 'foo',
/* Can't autocomplete `component` here */
},
])

// also BaseTheme with no mapped types doesn't work too

declare function extendTheme4(
extensions: Extensions
): Extensions

extendTheme4([
{
requiredField: 'foo',
/* Can't autocomplete `component` here */
},
])

// no extend tuple works

declare function extendTheme5<
Extensions extends AllPartialObject & Record,
>(extensions: [Extensions]): Extensions

extendTheme5([
{
/* Can autocomplete `component` here */
},
])
```

Original issue: https://github.com/microsoft/TypeScript/issues/45617

まず、issue の TypeScript の例を使って VS Code で extendTheme1 から extendTheme5 までの補完の違いを再現し、次にリンクされている元の issue と動作を比較します。現在失敗しているジェネリックタプルと mapped type のケースでコンポーネント補完が表示され、動作している例にリグレッションがないことを確認できれば完了です。

索引モデルが issue の本文から書いたものです。