Standardize notebook table-relationship documentation cells

cluster_analysis.ipynb

@@ -916,6 +916,28 @@
     "print('Top non-metro watersheds (RUCA 4-10):')\n",
     "nm_ws.head(15).reset_index(drop=True)\n"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "25",
+   "metadata": {},
+   "source": [
+    "## Tables Created by This Notebook and Their Relationships\n",
+    "\n",
+    "### Tables Created / Maintained\n",
+    "1. `public.ruca_codes_2020_tract`\n",
+    "- Tract-level RUCA lookup loaded from `new/RUCA-codes-2020-tract.csv`.\n",
+    "- Rebuilt with drop + recreate during load.\n",
+    "- Primary key: `tract_fips_20`.\n",
+    "\n",
+    "### Key Relationships\n",
+    "- `public.master_data_centers (geoid)`\n",
+    "  - many-to-1 -> `public.ruca_codes_2020_tract (tract_fips_20)`\n",
+    "\n",
+    "### Rerun Notes\n",
+    "- Rerunning refreshes the RUCA lookup table from the latest CSV.\n",
+    "- Downstream joins in this notebook read from this table but do not create additional persistent analysis tables."
+   ]
   }
  ],
  "metadata": {