Summary

Synchronize semantic symbol flags with the JavaScript emitted when lowering TypeScript enums.

• Mark top-level lowered enums as function-scoped variables.
• Mark exported and nested lowered enums as block-scoped variables.
• Remove enum flags when lowering a merged enum to an assignment, while preserving flags from the existing runtime declaration.
• Defer updates until program exit so enum inlining and removal can still identify enums during traversal.

This removes over 1,000 stale symbol-flag mismatches from semantic and transform-conformance snapshots.

Why Pending?

We delay it because SymbolFlags::RegularEnum/ConstEnum is still analysis input for the rest of traversal.

For example:

enum E {
  A = 1,
  B = foo(),
}
const x = E.A;

E is lowered when enter_statement visits the enum. Later, enter_expression visits E.A and checks the symbol flags to recognize and inline the enum member.

If lowering immediately changed E to FunctionScopedVariable, E.A would no longer be recognized as an enum, so the optimization would be skipped.

Thus the flags temporarily serve two roles:

1. During traversal: describe the original TypeScript enum for analysis and inlining.
2. After transformation: describe the emitted JavaScript binding (var, let, or a merged declaration).

Applying pending flags in exit_program updates them only after all enum-aware analysis is finished. It does not strictly need to be “at the end” if we introduced separate original/final flag storage, but with one shared SymbolFlags value, deferral is the simplest correct approach.