Narrowed `const` variables are widened in block-scoped closures

### 🔎 Search Terms

narrowing, cfa, closure,

### 🕗 Version & Regression Information

- This is the behavior in every version I tried, and I reviewed the FAQ for entries about n/a

### ⏯ Playground Link

https://www.typescriptlang.org/play/?noUncheckedIndexedAccess=true&target=99&ts=5.8.0-dev.20250209#code/CYUwxgNghgTiAEYD2A7AzgF3mgXNjMAligOYDcAUBYQGbwAUa8AvK-AOQ1JLsCU8AbwrwRiVJmwBBCIShNm2SqPg0ArijAZCqeACMowevyHLlydFi5I8nbuxaLhogL5VlajVp0luh409MxCxVuGyt7BTRpWTQlFwpXChAADwAHJBgsAWcgA

### 💻 Code

```ts
declare const s: string;

if (s === 'foo') {
function bad() {
const foo: 'foo' = s;
}
}

// in non-strict code bad() might be accessible outside of the narrowed branch,
// so make sure we're strict
export {}
```

### 🙁 Actual behavior

error trying to use the variable as its narrowed value.

### 🙂 Expected behavior

No error. `bad()` is a local function only reachable within the scope in which `s` has been definitely narrowed to `'foo'`.

### Additional Information

Found organically in https://github.com/typescript-eslint/typescript-eslint/pull/10182#discussion_r1948337564 (with a narrowed member access corollary)

Start with the linked TypeScript Playground repro and the code sample showing a narrowed const inside a block-scoped function. Trace how control-flow narrowing is handled for local function declarations and verify that the example no longer reports an error while preserving the strict-mode behavior described in the issue.

Written by the indexing model from the issue text.