Add optional cutscene field to move schema

Lets a move reference a cutscene to play when used, resolved by name
the same way a CUTSCENE item's "name" field is. Still just a schema
placeholder - no loader consumes moves.jsonc yet.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

assets/battle/moves.jsonc

@@ -8,7 +8,11 @@
       "ability": "FIRE",
       "power": 12,
       "mpCost": 4,
-      "target": "SINGLE_ENEMY"
+      "target": "SINGLE_ENEMY",
+      // Optional - name of a cutscene (see assets/cutscenes/) to play
+      // when this move is used, resolved lazily like a CUTSCENE item's
+      // "name" field. Omit for a move with no special presentation.
+      "cutscene": "battle/fire"
     }
   }
 }