Report network disconnects during approval (#39284)

## Why

When a local proxy request disconnects before network approval completes, the
owning tool call needs a model-visible explanation instead of remaining tied to
the abandoned request.

## What changed

- Track disconnect timing while plain HTTP and CONNECT requests await policy
  decisions.
- Cancel the owning execution and report how long the request waited when it
  disconnects before approval completes.
- Preserve an explicit approval outcome when disconnect cleanup runs afterward.

## Testing

Added unit coverage for disconnect tracking and outcome precedence, plus
end-to-end coverage for plain HTTP and CONNECT requests.

GitOrigin-RevId: b354b29bbe86f38e252fcaf529541f177480136b

codex-rs/exec-server/src/client_recovery.rs

@@ -704,6 +704,7 @@ impl ExecServerClient {
                                 command: None,
                                 exec_policy_hint: None,
                                 execution_id: None,
+                                disconnect: None,
                             });
                         let inner = Arc::downgrade(&inner);
                         let rpc_client = Arc::downgrade(&rpc_client);