feat(auto-review) short-circuit (#18890)

## Summary
Short circuit the convo if auto-review hits too many denials

## Testing
- [x] Added unit tests

---------

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

codex-rs/app-server-protocol/src/protocol/common.rs

@@ -1061,6 +1061,7 @@ server_notification_definitions! {
     ContextCompacted => "thread/compacted" (v2::ContextCompactedNotification),
     ModelRerouted => "model/rerouted" (v2::ModelReroutedNotification),
     Warning => "warning" (v2::WarningNotification),
+    GuardianWarning => "guardianWarning" (v2::GuardianWarningNotification),
     DeprecationNotice => "deprecationNotice" (v2::DeprecationNoticeNotification),
     ConfigWarning => "configWarning" (v2::ConfigWarningNotification),
     FuzzyFileSearchSessionUpdated => "fuzzyFileSearch/sessionUpdated" (FuzzyFileSearchSessionUpdatedNotification),

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -7250,6 +7250,16 @@ pub struct WarningNotification {
     pub message: String,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct GuardianWarningNotification {
+    /// Thread target for the guardian warning.
+    pub thread_id: String,
+    /// Concise guardian warning message for the user.
+    pub message: String,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]