[refactor] move rbm.torch → compat.torch

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

mnist_test.ipynb

@@ -24,7 +24,7 @@
     "from rbm.model import Model\n",
     "from rbm.entity import Entity, EntityParams, TrainingParams\n",
     "from rbm.matrix import Mat, np, rms_error_accu\n",
-    "from rbm.torch import Optimizer\n",
+    "from compat.torch import Optimizer\n",
     "import math"
    ]
   },
@@ -430,4 +430,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}