[codex] Enable apply_patch freeform by default (#21687)

## Summary
- enable `apply_patch_freeform` by default in the feature registry

## Why
- make the freeform `apply_patch` tool available by default when model
metadata does not explicitly opt into another mode

## Validation
- `just fmt`
- did not run tests

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/features/src/lib.rs

@@ -818,8 +818,8 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::ApplyPatchFreeform,
         key: "apply_patch_freeform",
-        stage: Stage::UnderDevelopment,
-        default_enabled: false,
+        stage: Stage::Stable,
+        default_enabled: true,
     },
     FeatureSpec {
         id: Feature::ApplyPatchStreamingEvents,

codex-rs/features/src/tests.rs

@@ -578,7 +578,7 @@ fn materialize_resolved_enabled_writes_all_features_and_preserves_custom_config(
         FeatureConfigSource::default(),
         FeatureOverrides::default(),
     );
-    assert_eq!(replayed.enabled(Feature::ApplyPatchFreeform), false);
+    assert_eq!(replayed.enabled(Feature::ApplyPatchFreeform), true);
 }
 
 #[test]