Feature request: allow starting a new goal immediately after completing one

Feature request

When an agent completes an active goal, it would be useful for the goal lifecycle to support an immediate handoff into a new goal in the same session.

Right now, completing a goal feels like an endpoint. In practice, users often treat a goal as one bounded checkpoint in a longer workflow: finish the current objective, record it as complete, then continue directly into the next objective without needing to restart the flow manually.

Desired behavior

After a goal is completed, Codex should provide a clean way for the agent or user to start a new goal immediately, while preserving the completed goal's final state and usage/accounting details.

This could look like one of these options:

• an explicit start_next_goal style action after completion
• allowing create_goal once the previous goal has just been marked complete
• a UI/CLI affordance that offers "Start next goal" after successful completion

Why this helps

This would make goals work better for multi-step projects where each goal is intentionally scoped, but the overall task continues. It also avoids making users choose between overly broad goals and repeatedly re-entering goal mode for each next phase.

Related: #24978 and #28430 discuss completed goals remaining active or needing clearer completion/clearing behavior. This request is specifically about making the next-goal handoff a first-class workflow, not treating it as a bug.