change model cap to server overload (#11388)

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codex-rs/protocol/src/protocol.rs

@@ -978,10 +978,7 @@ pub enum AgentStatus {
 pub enum CodexErrorInfo {
     ContextWindowExceeded,
     UsageLimitExceeded,
-    ModelCap {
-        model: String,
-        reset_after_seconds: Option<u64>,
-    },
+    ServerOverloaded,
     HttpConnectionFailed {
         http_status_code: Option<u16>,
     },