Feature Request: Show ACP/exec-spawned sessions in Codex app (with toggle/filter)

Feature Request

Summary: Add an option to surface ACP/exec-spawned sessions in the Codex app alongside interactive sessions.

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Problem

When orchestrating Codex via ACP or codex_mcp, all coding work happens invisibly — sessions are stored in ~/.codex/sessions/ as JSONL but never appear in the Codex app. The only way to review them is through the CLI.

For teams using Codex as a background coding agent (orchestrated by tools like OpenClaw, custom scripts, or CI pipelines), this creates real friction:

• No way to audit what an ACP-spawned Codex session actually did
• Can't review diffs, reasoning, or conversation history without dropping to the terminal
• Context-switching between the app (for interactive sessions) and CLI (for ACP sessions) breaks the workflow

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Proposed Solution

Add a toggle or filter in the Codex app session list:

• Default view: Interactive only (current behavior, no regression)
• Optional view: All sessions — includes ACP/exec-spawned sessions, clearly tagged (e.g. [ACP], [exec])

This preserves the intentional separation while giving power users visibility into their full Codex session history.

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Why This Matters

As Codex becomes a core component in multi-agent workflows, the app is the natural place to review and audit all Codex work — not just the interactive kind. The session data already exists; surfacing it is the missing piece.

Even a read-only view of ACP sessions in the app would dramatically improve the experience for anyone using Codex as a background agent.

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Environment

• Codex CLI: latest
• macOS arm64
• Orchestration: OpenClaw ACP / codex-acp adapter

Related to issue #16385