feat(rune): Implement qr operation

Author: ColonelToad

rune/lib/nx_rune.ml

@@ -611,7 +611,16 @@ let op_irfft (type a c) (t : (Complex.t, a) t) ~(dtype : (float, c) Dtype.t)
 let op_cholesky ~upper:_ _ =
   failwith "op_cholesky: not implemented in Rune backend"
 
-let op_qr ~reduced:_ _ = failwith "op_qr: not implemented in Rune backend"
+let op_qr ~reduced t_in =
+  try
+    (* No effect for qr currently; perform directly on native tensors. *)
+    match t_in with
+    | Native_tensor t ->
+        let q, r = Nx_c.op_qr ~reduced t in
+        (Native_tensor q, Native_tensor r)
+    | Symbolic_tensor _ -> failwith "op_qr: symbolic tensors not supported in Rune backend"
+  with Effect.Unhandled _ -> failwith "op_qr: not implemented in Rune backend"
+
 
 let op_svd ~full_matrices:_ _ =
   failwith "op_svd: not implemented in Rune backend"