[FEATURE] Start, read, and stop cloud sessions headlessly, like subagents

Ask: let a running session (or claude -p) start a cloud session with a task, read its replies, and stop it — the lifecycle subagents already have.

Works today (2.1.281): claude -p "<msg>" --cloud <session-id> sends to an existing cloud session ("Sent to cloud session.").

Missing:

1. Start — claude --cloud "<task>" -p is refused ("interactive only"); so is --cloud --bg.
2. Read — no CLI way to fetch a cloud session's reply after a send.
3. Stop — no CLI way to stop or archive one.
4. List — a local session can't see my cloud sessions.

Possible shape: claude --cloud "<task>" -p --output-format json → prints the new session id · --cloud <id> --read → latest reply · --cloud <id> --stop. Or remote isolation for the Agent tool on individual plans.

Related: #97361 (Agent isolation: "remote" runs as a local worktree) · #97446 (archive cloud sessions programmatically).

Workaround: I start one cloud session by hand; my local session sends it tasks with claude -p … --cloud <id>, and it pushes results as git branches.

---

AI-assisted.