@JCState drops generic arguments from property types

[schwa]

  import JCState
  import simd

  @JCState
  struct S {
      var v: SIMD3<Float> = .init(0, 0, 0)
  }

Compile errors in the expansion: "reference to generic type 'SIMD3' requires arguments in <...>" and "generic parameter 'Scalar' could not be inferred". The macro emits bare SIMD3 instead of SIMD3.