Move item occurrences to canonical namespace

internal/modules/integration/testdata/seriatim_item_occurrences_session.json

@@ -0,0 +1,12 @@
+{
+  "metadata": {
+    "id": "item-occurrences-session",
+    "title": "Synthetic D&D item-occurrence session"
+  },
+  "segments": [
+    {"id": 1, "start": 0, "end": 4, "speaker": "DM", "text": "An ancient coin rests in the chest."},
+    {"id": 2, "start": 4, "end": 8, "speaker": "DM", "text": "The party acquires 25 gold pieces."},
+    {"id": 3, "start": 8, "end": 12, "speaker": "DM", "text": "Aria gives Borin a healing potion."},
+    {"id": 4, "start": 12, "end": 16, "speaker": "DM", "text": "The party continues down the road."}
+  ]
+}