chore: move SPDX header in notebook to first code cell (#300)

## Summary
- Move SPDX copyright/license header from a raw cell at the top of the
101 tutorial notebook into the first code cell as Python comments
- Raw cells render poorly in some notebook viewers; placing the header
in the code cell ensures visibility and passes the copyright check

## Test plan
- [x] Notebook renders correctly in JupyterLab / VS Code / GitHub
- [x] Copyright check CI passes

Made with [Cursor](https://cursor.com)

---------

Signed-off-by: Kendrick Boyd <kendrickb@nvidia.com>

Author: kendrickb-nvidia

docs/tutorials/safe-synthesizer-101.ipynb

@@ -1,14 +1,5 @@
 {
   "cells": [
-    {
-      "cell_type": "raw",
-      "id": "6808567a",
-      "metadata": {},
-      "source": [
-        "<!-- SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. -->\n",
-        "<!-- SPDX-License-Identifier: Apache-2.0 -->"
-      ]
-    },
     {
       "cell_type": "markdown",
       "id": "d1d7a7a3",
@@ -48,6 +39,9 @@
       "outputs": [],
       "source": [
         "%%capture\n",
+        "# SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.\n",
+        "# SPDX-License-Identifier: Apache-2.0\n",
+        "\n",
         "#TODO: Replace the internal NVIDIA Artifactory endpoint with the public PyPI release when available.\n",
         "!uv pip install nemo-safe-synthesizer[engine,cu128] --extra-index-url \"https://urm.nvidia.com/artifactory/api/pypi/nv-shared-pypi-local/simple\"\n",
         "!uv pip install datasets\n"