fix: async-ify login flow (#2393)

This replaces blocking I/O with async/non-blocking I/O in a number of
cases. This facilitates the use of `tokio::sync::Notify` and
`tokio::select!` in #2394.









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[//]: # (BEGIN SAPLING FOOTER)
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* #2399
* #2398
* #2396
* #2395
* #2394
* __->__ #2393
* #2389

codex-rs/cli/src/login.rs

@@ -21,7 +21,7 @@ pub async fn login_with_chatgpt(codex_home: PathBuf) -> std::io::Result<()> {
         server.actual_port, server.auth_url,
     );
 
-    server.block_until_done()
+    server.block_until_done().await
 }
 
 pub async fn run_login_with_chatgpt(cli_config_overrides: CliConfigOverrides) -> ! {