Never-initialized variable type is not narrowed to undefined

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### 🔎 Search Terms

narrow uninitialized, uninitialized undefined

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about `initialized`/`uninitialized`

### ⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.9.0-dev.20250326#code/MYewdgzgLgBAZiEMC8MAUUDuIBcNoBOAlmAOYCUeAbiEQCYoB8MA3gFAwwBEArhAKb4oxYFC4BuDjCkB6GTH4QANiSgBaOkQgBDAEZL+asPwAe6lcZgABKAE8ADouDF76xRagySRdXX7AlbQJtKCJwCCkDWHB+PEISUhgAHxgeMD84En46SSkiOHQYlGRULBByVilOORgAPQB+KpgagDlEeykAXzZutgQQNC4ucnEgA

### 💻 Code

```ts
const foo = (two: string): void => {
"use strict";

// eslint-disable-next-line @typescript-eslint/init-declarations
let one: string | undefined;

if (one === two) {
// ^? let one: string | undefined
// Noop
}
}

foo("");
```

### 🙁 Actual behavior

The type is not narrowed, which prevents typescript-eslint from flagging this comparison that always fails: [typescript-eslint playground](https://typescript-eslint.io/play/#ts=5.7.2&fileType=.tsx&code=MYewdgzgLgBAZiEMC8MAUUDuIBcNoBOAlmAOYCUeAbiEQCYoB8MA3gFAwwBEArhAKb4oxYFC4BuDjCkB6GTH4QANiSgBaOkQgBDAEZL%2BasPwAe6lcZgABKAE8ADouDF76xRagySRdXX7AlbQJtKCJwCCkDWHB%2BPEISUhgAHxgeMD84En46SSkiOHQYlGRULBByVilOORgAOUR7KQBfNha2BBA0Li5ycSA&eslintrc=N4KABGBECmAeAu0B2ATAzpAXGA2uCU0aANgJZLyYCGxxkANPhJAA7ECuA5uZgALwBPFkQDGAJ1It4AWiJkKAehp18AXUbMx7YkSxhQEAL4hDQA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false)

### 🙂 Expected behavior

The `one === two` comparison should be flagged because it always returns false (there is no way `one` has any value other than `undefined`).

### Additional information about the issue

Also filed a related issue with ESLint: https://github.com/eslint/eslint/issues/19581

Riproduci il comportamento usando il link a TypeScript Playground e l’esempio `one === two`, quindi traccia come il narrowing del flusso di controllo gestisce una variabile mai inizializzata. Confronta il risultato con il confronto atteso sempre falso e usa l’issue di ESLint collegata per il contesto correlato. Il lavoro è completato quando il confronto viene riconosciuto come impossibile senza modificare il comportamento del narrowing non correlato.

Scritto dal modello di indicizzazione a partire dal testo della issue.