Add Qwen vision loading and Metal inference

src/engine/metal/qwen_mtplx/unary.rs

@@ -15,12 +15,12 @@ pub(super) enum Unary {
     #[cfg_attr(not(test), expect(dead_code, reason = "Reference diagnostic API"))]
     Log,
     Sigmoid,
-    #[cfg_attr(not(test), expect(dead_code, reason = "Reference diagnostic API"))]
     Tanh,
     Sqrt,
     Rsqrt,
     Sin,
     Cos,
+    Erf,
 }
 
 pub(super) fn unary(input: &Array, op: Unary, stream: Stream) -> Result<Array, String> {