Fix swiftfox model selector (#3598)

The model shouldn't be saved with a suffix. The effort is a separate
field.

codex-rs/common/src/model_presets.rs

@@ -25,22 +25,22 @@ pub fn builtin_model_presets() -> &'static [ModelPreset] {
             id: "swiftfox-low",
             label: "swiftfox low",
             description: "",
-            model: "swiftfox-low",
-            effort: None,
+            model: "swiftfox",
+            effort: Some(ReasoningEffort::Low),
         },
         ModelPreset {
             id: "swiftfox-medium",
             label: "swiftfox medium",
             description: "",
-            model: "swiftfox-medium",
+            model: "swiftfox",
             effort: None,
         },
         ModelPreset {
             id: "swiftfox-high",
             label: "swiftfox high",
             description: "",
-            model: "swiftfox-high",
-            effort: None,
+            model: "swiftfox",
+            effort: Some(ReasoningEffort::High),
         },
         ModelPreset {
             id: "gpt-5-minimal",