[codex] Add chat-v2 attach-or-embed startup

[roackb2]

Summary

Adds the PR 3 chat-v2 startup behavior on top of the merged server lifecycle split.

• Keeps chat-v2 bootstrap ownership inside src/cli-v2: runtime resolution lives in src/cli-v2/runtime.ts and the command runner lives in src/cli-v2/index.tsx.
• Leaves src/cli/main.ts as the command router only; it dispatches chat-v2 to runChatCliV2.
• Attaches to a fresh live control-plane server when one is registered.
• Starts an embedded embedded-chat control-plane server when no fresh live server exists, using the shared startHeddleControlPlaneServer path and an OS-assigned local port.
• Keeps cli-v2 as the API consumer by passing trpcUrl and the CLI-selected workspaceId through the existing store/client path.
• Returns Ink render state from startChatCliV2 so the v2 runner can close the embedded server after the TUI exits.

Expected behavior change

yarn chat:dev:v2 no longer requires a pre-running heddle daemon or yarn server:dev.

Expected user-visible behavior:

• If a fresh live control-plane server is registered, chat-v2 prints that it is attaching and uses that server.
• If no fresh live server exists, chat-v2 starts an embedded local control-plane server, prints its endpoint/serverId, and opens the TUI against it.
• The TUI still owns its initial active workspace by passing the current workspace id into the shared API client.
• A second chat-v2 process should attach to the first embedded/live server instead of starting another server, assuming the first server remains registered and fresh.

This PR does not do the later PR 4 cleanup of request-workspace assumptions, logging placement, or heartbeat catalog ownership.

How to verify

Manual smoke:

1. Ensure no Heddle control-plane server is running.
2. Run yarn chat:dev:v2.
3. Confirm it prints started embedded chat-v2 control-plane server and enters the TUI.
4. In another terminal, run yarn cli:dev daemon and confirm it prints the existing server address/serverId and exits successfully.
5. Stop the TUI, then run yarn chat:dev:v2 again to confirm it can start a new embedded server.
6. With yarn server:dev already running, run yarn chat:dev:v2 and confirm it prints attaching chat-v2 to the live control-plane server.

Automated checks run locally:

• yarn -s vitest run src/tests/unit/cli-v2/chat-v2-runtime.test.ts src/tests/unit/cli/main-command-routing.test.ts
• yarn typecheck
• yarn lint
• Earlier on this branch before the ownership move: yarn test and yarn build

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Close the TUI before awaiting embedded shutdown

When an external SIGTERM/SIGINT reaches an embedded chat-v2 process after the TUI has started, this handler awaits runtime.close() while the mounted app still owns live tRPC/EventSource subscriptions (ControlPlaneSessionSubscriptionService only unsubscribes from App unmount). The HTTP server close path waits for active connections to finish, so those open subscriptions can keep runtime.close() from resolving and the .finally(process.exit) path is never reached. The signal path should first unmount/dispose the Ink app or otherwise force-close client/server connections before awaiting the server close.

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