address review: exclude bool from coercion, parameterize tests over all fields

Agent-Logs-Url: https://github.com/dylanlangston/nextcloud-mcp-server/sessions/0360ab28-8913-450e-8c61-697e71ba9742

Co-authored-by: dylanlangston <16236219+dylanlangston@users.noreply.github.com>

nextcloud_mcp_server/models/cookbook.py

@@ -63,6 +63,8 @@ class Nutrition(BaseModel):
         strings (e.g. '650 kcal') or numbers (e.g. 650). Nextcloud Cookbook
         stores whatever the source provided.
         """
+        if isinstance(v, bool):
+            return v
         if isinstance(v, (int, float)):
             return str(v)
         return v