note: Queue routing checked. Remote worker-runtime process connection depends on WebSocket observation proxy `00001KVZKSTJT` and REST command server `00001KVZKSTE2`; REST is now inprogress and WS proxy remains queued, so this Ticket should wait.

author: yoi-orchestrator


note: Dependencies are now done: FS store, REST command server, WebSocket observation proxy, and RuntimeRegistry foundation. Related profile/config sync is not a blocking relation for v0, per existing relation note.

summary: Backend RuntimeRegistry に remote worker-runtime process handle を追加し、REST command API と WS observation API を Backend-owned client として route/proxy できるようにする。Dynamic registration/full auth/Web Console/Profile sync は扱わない。

role_plan: Orchestrator が dedicated child worktree を作成し、coder Worker に `crates/workspace-server` と必要な Cargo/package files の write scope を委譲する。reviewer Worker は read-only で remote endpoint/token non-leak、runtime_id+worker_id authority、REST/WS client error mapping、embedded/local separation を確認する。merge/validation/done/cleanup は Orchestrator が行う。