Notify lifecycle extensions of compaction usage limits (#49097)

## Why

Usage-limit failures during manual or post-turn compaction did not notify turn lifecycle extensions, leaving them unable to react to these errors.

## What changed

Emit the turn error lifecycle notification for `UsageLimitExceeded` in both compaction paths. Preserve the completed answer after post-turn compaction fails, and avoid duplicating the error already emitted by manual compaction.

GitOrigin-RevId: f31155e5991d762a0779030921aedbd1f818cfbb

codex-rs/core/src/session/turn.rs

@@ -736,6 +736,12 @@ pub(crate) async fn run_turn(
                         ) {
                             return Err(err);
                         }
+                        let error = err.to_codex_protocol_error();
+                        if matches!(error, CodexErrorInfo::UsageLimitExceeded) {
+                            // Preserve the completed answer while stopping automatic work.
+                            sess.emit_turn_error_lifecycle(turn_context.as_ref(), error)
+                                .await;
+                        }
                         warn!(error = %err, "Post-turn compaction failed; preserving the completed turn");
                     }
                     break;