Mark codex_hooks stable (#19012)

# Why

Hooks are ready to graduate to GA in the next release!

# What

- Moves `Feature::CodexHooks` into the stable feature group.
- Marks the `codex_hooks` feature spec as `Stage::Stable` and
default-enabled.

codex-rs/features/src/lib.rs

@@ -75,6 +75,8 @@ pub enum Feature {
     GhostCommit,
     /// Enable the default shell tool.
     ShellTool,
+    /// Enable Claude-style lifecycle hooks loaded from hooks.json files.
+    CodexHooks,
 
     // Experimental
     /// Enable JavaScript REPL tools backed by a persistent Node kernel.
@@ -95,8 +97,6 @@ pub enum Feature {
     ApplyPatchStreamingEvents,
     /// Allow exec tools to request additional permissions while staying sandboxed.
     ExecPermissionApprovals,
-    /// Enable Claude-style lifecycle hooks loaded from hooks.json files.
-    CodexHooks,
     /// Expose the built-in request_permissions tool.
     RequestPermissionsTool,
     /// Allow the model to request web searches that fetch live content.
@@ -751,8 +751,8 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::CodexHooks,
         key: "codex_hooks",
-        stage: Stage::UnderDevelopment,
-        default_enabled: false,
+        stage: Stage::Stable,
+        default_enabled: true,
     },
     FeatureSpec {
         id: Feature::RequestPermissionsTool,