fix: labeled statements emit compile error instead of silent wrong results

[cs01]

Summary

• Labeled statements (e.g., outer: for ... break outer) were silently dropped by both parsers, causing wrong results at runtime
• Both parsers now emit a clear compile error suggesting to use a flag variable with regular break instead
• Native parser uses if check before switch (workaround for native switch codegen not matching certain string cases)

Test plan

• New test fixture edge-cases/labeled-statement.ts with @test-compile-error
• Both node and native compilers reject labeled statements
• npm run verify:quick passes