chore: add ipykernel dependency and update notebooks

- Add ipykernel to project dependencies for Jupyter notebook support
- Update BPE and GPT analysis notebooks with latest experiments

notebooks/bpe.ipynb

@@ -98,21 +98,10 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 1,
    "id": "e8c52a53",
    "metadata": {},
-   "outputs": [
-    {
-     "ename": "",
-     "evalue": "",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[1;31mRunning cells with '.venv (Python 3.10.9)' requires the ipykernel package.\n",
-      "\u001b[1;31mInstall 'ipykernel' into the Python environment. \n",
-      "\u001b[1;31mCommand: '/Users/sergey/Projects/ML/llm-arch-research/.venv/bin/python -m pip install ipykernel -U --force-reinstall'"
-     ]
-    }
-   ],
+   "outputs": [],
    "source": [
     "import dill\n",
     "\n",
@@ -269,7 +258,15 @@
    "name": "python3"
   },
   "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
    "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
    "version": "3.10.9"
   }
  },