Add model availability NUX metadata

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

@@ -22,6 +22,16 @@
     },
     "Model": {
       "properties": {
+        "availabilityNux": {
+          "anyOf": [
+            {
+              "$ref": "#/definitions/ModelAvailabilityNux"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
         "defaultReasoningEffort": {
           "$ref": "#/definitions/ReasoningEffort"
         },
@@ -82,6 +92,21 @@
       ],
       "type": "object"
     },
+    "ModelAvailabilityNux": {
+      "properties": {
+        "id": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "id",
+        "message"
+      ],
+      "type": "object"
+    },
     "ReasoningEffort": {
       "description": "See https://platform.openai.com/docs/guides/reasoning?api-mode=responses#get-started-with-reasoning",
       "enum": [