fix: skip block-scoped variable check for label identifiers

[Ankitajainkuniya]

Summary

Fixes #30408

Labels and variables occupy separate namespaces in JavaScript/TypeScript. When a label name coincides with a later let/const variable declaration, the compiler incorrectly reports "Block-scoped variable 'foo' used before its declaration" on the label.

Repro

foo: while (true) {
    break foo;
}
let foo = 1;

Before: Error TS2448 on foo: and break foo — "Block-scoped variable 'foo' used before its declaration"
After: No error (correct behavior — foo: is a label, not a variable reference)

Fix

Added a guard in checkResolvedBlockScopedVariable (checker.ts) that skips the "used before declaration" check when the identifier is:

• The label of a LabeledStatement (e.g., foo: while (...))
• The label of a BreakStatement or ContinueStatement (e.g., break foo)

Regression Test

Normal "used before declaration" errors still fire correctly:

console.log(x); // TS2448: Block-scoped variable 'x' used before its declaration ✓
let x = 1;

Test Case

Added tests/cases/conformance/statements/labeledStatements/labeledStatementWithBlockScopedVariable.ts covering:

• Label before let variable with break
• Label before const variable with continue
• Nested labeled statements with same-name variables

[RyanCavanaugh]

@Ankitajainkuniya what agent did you use to write this?

[Ankitajainkuniya]

@Ankitajainkuniya what agent did you use to write this?

@RyanCavanaugh I used OpenAI as a coding assistant for parts of this, with my own review and modifications. The architecture decisions and product logic are mine the AI helped with implementation speed.

I'm building several open-source projects with this workflow: github.com/Ankitajainkuniya

[RyanCavanaugh]

Please have your workflow ingest https://github.com/microsoft/TypeScript/blob/main/CONTRIBUTING.md before proceeding.