chore(improvements): 🔧 Update hunting grounds improvement data in JSON config file

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

public/resources/improvements/hunting_grounds.json

@@ -0,0 +1,23 @@
+{
+  "id": "hunting_grounds",
+  "name": "Hunting Grounds",
+  "description": "Managed wilderness where trappers and hunters harvest game from the surrounding fauna",
+  "build_turns": 5,
+  "valid_terrain": [
+    "forest",
+    "boreal_forest",
+    "jungle",
+    "tundra"
+  ],
+  "yields": {
+    "food": 1,
+    "culture": 1
+  },
+  "effects": {},
+  "encyclopedia": {
+    "category": "civilization",
+    "entry_type": "improvement",
+    "detail_route": "/buildings/improvements",
+    "tags": []
+  }
+}