Add remote skill scope/product_surface/enabled params and cleanup (#11801)

skills/remote/list: params=hazelnutScope, productSurface, enabled;
returns=data: { id, name, description }[]
skills/remote/export: params=hazelnutId; returns={ id, path }

codex-rs/app-server-protocol/schema/json/v2/SkillsRemoteWriteResponse.json

@@ -4,18 +4,14 @@
     "id": {
       "type": "string"
     },
-    "name": {
-      "type": "string"
-    },
     "path": {
       "type": "string"
     }
   },
   "required": [
     "id",
-    "name",
     "path"
   ],
   "title": "SkillsRemoteWriteResponse",
   "type": "object"
-}
+}