[REMOTE-2616] Spec: recover run_agents after GitHub authentication

[warp-agent-staging]

Description

Spec only (no Rust). Recovers an accepted run_agents action when remote children need GitHub authentication.

Please approve the two gated decisions before implementation:

1. Status shape: add AIActionStatus::BlockedOnUserAction; keep the action in running_actions; do not reuse pending-approval Blocked or requeue.
2. Partial-batch semantics: project that status whenever any child is recoverably auth-blocked (including mixed launched/failed/launching/retrying siblings); return to RunningAsync only when no blocker remains and automated work continues.

Linear: REMOTE-2616

Linked Issue

• The linked issue is labeled ready-to-spec or ready-to-implement.
• Where appropriate, screenshots or a short video of the implementation are included below (especially for user-visible or UI changes).

Testing

Spec-only change. No runtime behavior change in this PR.

• I have manually tested my changes locally with ./script/run

Agent Mode

• Warp Agent Mode - This PR was created via Warp's AI Agent Mode

CHANGELOG-NONE

[warp-agent-staging]

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