docs: replace native 'int' with core type 'uint16' in custom-codecs tutorial

- Changed conn_id : int → conn_id : uint16 in Connectivity table
- Changed unit_id : int → unit_id : uint16 in Unit table
- Python dataclass SpikeTrain.unit_id: int unchanged (Python type, not DJ type)
- Aligns with core type standards from TERMINOLOGY.md

Author: dimitri-yatsenko

src/tutorials/advanced/custom-codecs.ipynb

@@ -113,7 +113,7 @@
     "@schema\n",
     "class Connectivity(dj.Manual):\n",
     "    definition = \"\"\"\n",
-    "    conn_id : int\n",
+    "    conn_id : uint16\n",
     "    ---\n",
     "    network : <graph>\n",
     "    \"\"\""
@@ -253,7 +253,7 @@
     "@schema\n",
     "class Unit(dj.Manual):\n",
     "    definition = \"\"\"\n",
-    "    unit_id : int\n",
+    "    unit_id : uint16\n",
     "    ---\n",
     "    spikes : <spike_train>\n",
     "    \"\"\"\n",
@@ -304,4 +304,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 5
-}
+}