Delegated sessions are not renamed with a representative identifier in Codex

Description:
When Codex Companion delegates tasks, the resulting sessions appear in the Codex session list with the generic name Codex Companion Task: <task> l... instead of replacing <task> with an actual representative identifier.

Current behavior:
All delegated sessions show identical, unresolved names like Codex Companion Task: <task> l..., making them indistinguishable from each other.

Expected behavior:
Each session should display a meaningful name such as Codex Companion Task: fix-auth-bug or Codex Companion Task: #1234, so the user can identify each task at a glance.

Impact:
When multiple tasks are running in parallel (as shown in the screenshot, up to 5 simultaneous sessions), it is impossible to tell them apart without opening each one individually.

Possible cause:
The <task> placeholder is not being interpolated when naming the session, or the task identifier is not being passed correctly at session creation time.

Steps to reproduce:

1. Delegate 2 or more tasks using Codex Companion
2. Observe the active sessions list in Codex

Start by tracing where Codex Companion creates sessions for delegated tasks and how the session name containing the placeholder is assembled. Reproduce the issue with two or more delegated tasks, then verify that each session displays a meaningful task identifier in the Codex session list.