fix(4087): fix declaration emit modifiers for constructor types

[a-tarasyuk]

Fixes #4087

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds a new compiler test case for declaration emit involving a constructor-typed var that shares a name with an interface, and updates declaration transformer modifier-flag computation to use combined AST modifier flags directly.

Changes:

• Added a new @declaration test case covering var Foo: new () => number alongside interface Foo in a namespace.
• Added new reference baselines for types, symbols, and JS/d.ts outputs for the new test.
• Updated modifier flag masking / detection to use ast.GetCombinedModifierFlags instead of host “effective” flags.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
testdata/tests/cases/compiler/declarationEmitConstructorType.ts	New regression test exercising declaration emit for constructor-typed variable vs interface name collision.
testdata/baselines/reference/compiler/declarationEmitConstructorType.types	Expected type baseline for the new test.
testdata/baselines/reference/compiler/declarationEmitConstructorType.symbols	Expected symbol baseline for the new test.
testdata/baselines/reference/compiler/declarationEmitConstructorType.js	Expected JS + d.ts baseline for the new test.
internal/transformers/declarations/util.go	Changes modifier flag masking to derive flags directly from AST combined modifiers.
internal/transformers/declarations/transform.go	Changes modifier comparison to use combined modifiers and updates call into maskModifierFlags.