Fix cross-file const inlining and flag const cycles

[chrisdp]

Summary

Fixes #1618.

When a const's value is an aa-literal (or other complex expression) containing enum or const references, and the const is consumed from a different file than where it was defined, the inner refs were left unresolved in the transpiled output. For example:

' map.bs
namespace name.space
    enum someEnum
        one = "val1"
    end enum
    const myMap = { "key1": someEnum.one }
end namespace

' helper.bs — different file
namespace name.space
    class someClass
        public function someFunc(key as dynamic) as object
            return name.space.myMap[key]
        end function
    end class
end namespace

Transpiled output (before this fix):

return ({
    "key1": someEnum.one  ' ← never replaced; crashes at runtime
})[key]

Why same-file worked but cross-file didn't

BrsFilePreTranspileProcessor.iterateExpressions walks the consumer file's parser.references.expressions and overrides each VariableExpression / DottedGetExpression's transpile to inline the resolved const/enum literal. When the const and consumer are in the same file, that pass coincidentally also visits the inner enum refs nested inside the const's aa-literal value. Cross-file, those AST nodes live in the defining file and the consumer's pass never visits them, so they emit their default someEnum.one text.

Fix

In processExpressionInNamespace, after resolving a const reference, if the resolved value is non-literal, walk it and apply the same const/enum substitution to every inner VariableExpression / DottedGetExpression (skipping inner parts of dotted chains, which are handled at the chain level). The walk is scoped to the const statement's containing namespace, since that's where the inner refs were authored, not the consumer's namespace.

The substitution uses the existing editor.setProperty('transpile', ...) mechanism; the editor undoes those overrides after the consumer file's transpile finishes, so the const's defining file isn't affected on subsequent transpile passes.

Tests

Two new tests in ConstStatement.spec.ts:

• resolves enum refs inside an aa-literal const used cross-file (issue #1618) — direct repro from the issue
• resolves enum refs in computed keys of an aa-literal const used cross-file — covers [someEnum.X]: value form