C# delegate declarations dropped, so in-file references mint a sourceless god node #4552

Version

v8 @ 0.9.92 (86c57be)

Problem

A C# delegate is a named type, but delegate_declaration is in neither class_types nor function_types, so the declaration is dropped. A field or parameter typed as the delegate still resolves the name through ensure_named_node, which mints a sourceless stub and points the references edge at it — even though the delegate is declared in the same file.

That violates the provenance invariant: a real source-backed declaration must not lose to a sourceless god node (and the bare-id stub becomes a cross-file hub shared by every same-named reference in the corpus).

Reproduce

public delegate int BinOp(int a, int b);
public class Calc {
    public BinOp Op;
    public int Apply(BinOp f, int x) { return f(x, x); }
}

BinOp appears as a node with empty source_file, and Calc/Apply reference that sourceless node.

Expected vs actual

• Expected: BinOp is a sourced node in the declaring file; references bind to it.
• Actual: BinOp is sourceless; references bind to the stub.

Notes

delegate_declaration has a name field and no body, so it emits a clean empty type node (no phantom members). Delegate parameter/return type refs and delegate-instance invocation resolution are out of scope.