Fix stack overflow in checkTypeExpandability()

[johnfav03]

Fixes an issue uncovered in #4380 (comment) (pixijs); checkTypeExpandibility() recurses into a reference type's type arguments, but it only stored the type on the typeStack around the shouldExpandType() calls. This means that self-referential types were never detected as already in-progress and could lead to a stack overflow error.

[Copilot]

Pull request overview

Fixes an infinite-recursion/stack-overflow scenario in the checker’s NodeBuilderImpl.checkTypeExpandability() when encountering self-referential reference-type type arguments during hover/QuickInfo verbosity expansion (pixijs Container pattern; issue #4380).

Changes:

• Keep the typeStack entry for the full duration of checkTypeExpandability() (including recursion into reference type arguments) and add an early cycle short-circuit to prevent unbounded recursion.
• Add a new hand-written fourslash regression test reproducing the self-referential default-type-arg loop.
• Add the corresponding quickInfo hover baseline for the new fourslash test.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
internal/checker/nodebuilderimpl.go	Fixes cycle tracking in checkTypeExpandability() so self-referential type arguments don’t recurse indefinitely.
internal/fourslash/tests/quickinfoVerbositySelfReferentialTypeArg_test.go	Adds regression coverage for the hover crash pattern from pixijs.
testdata/baselines/reference/fourslash/quickInfo/quickinfoVerbositySelfReferentialTypeArg.baseline	Stores expected hover output for the new regression test.