Expose ChatGPT user IDs in account/read responses (#60004)

## What changed

Add a nullable `userId` to `GetAccountResponse`, populated from the same authenticated account snapshot as the rest of the response. ChatGPT and personal access token sessions return the canonical ChatGPT user ID when available; API-only and signed-out sessions return `null`.

Update the cloud client, generated schemas, TypeScript and Python types, and account identity documentation. Default missing IDs to `None` when deserializing responses from older app servers.

## Testing

Extend account response tests to check ChatGPT and personal access token user IDs, null IDs for other providers and signed-out sessions, and ID changes when switching providers with saved ChatGPT credentials.

GitOrigin-RevId: 7ad3da3cfc835c4d08d03c8e91b06cd7e007d874

sdk/python/src/openai_codex/generated/v2_all.py

@@ -8923,6 +8923,13 @@ class GetAccountResponse(BaseModel):
     )
     account: Account | None = None
     requires_openai_auth: Annotated[bool, Field(alias="requiresOpenaiAuth")]
+    user_id: Annotated[
+        str | None,
+        Field(
+            alias="userId",
+            description="ChatGPT user ID belonging to this account response, when available.",
+        ),
+    ] = None
 
 
 class GuardianApprovalReview(BaseModel):