fix(app-server): for external auth, replace id_token with chatgpt_acc… (#11240)

…ount_id and chatgpt_plan_type

### Summary
Following up on external auth mode which was introduced here:
https://github.com/openai/codex/pull/10012

Turns out some clients have a differently shaped ID token and don't have
a chosen workspace (aka chatgpt_account_id) encoded in their ID token.
So, let's replace `id_token` param with `chatgpt_account_id` and
`chatgpt_plan_type` (optional) when initializing the external ChatGPT
auth mode (`account/login/start` with `chatgptAuthTokens`).

The client was able to test end-to-end with a Codex build from this
branch and verified it worked!

codex-rs/app-server/tests/common/mcp_process.rs

@@ -334,12 +334,14 @@ impl McpProcess {
     /// Send an `account/login/start` JSON-RPC request with ChatGPT auth tokens.
     pub async fn send_chatgpt_auth_tokens_login_request(
         &mut self,
-        id_token: String,
         access_token: String,
+        chatgpt_account_id: String,
+        chatgpt_plan_type: Option<String>,
     ) -> anyhow::Result<i64> {
         let params = LoginAccountParams::ChatgptAuthTokens {
-            id_token,
             access_token,
+            chatgpt_account_id,
+            chatgpt_plan_type,
         };
         let params = Some(serde_json::to_value(params)?);
         self.send_request("account/login/start", params).await