bug(runtime-host): paused Graph recovery retries admission and fails Host startup

### What happened

Recovering persisted Agent Graph work can prevent the entire Runtime Host from starting when the root Session cannot currently admit background execution: it is in Plan mode, or it is a legacy Session without an explicit `llmConnectionId`.

The supervisor retries the admission rejection three times, then its `onError` triggers Host drain. Startup subsequently fails with `Agent graph coordinator is closed` / `Runtime Host startup failed and shutdown did not complete cleanly`. Restarting the same data root repeats the three attempts.

Expected: preserve the durable checkpoint while that Session waits for explicit account selection / execution resume. The Host should become ready so the user can resolve the Session's configuration.

### How to reproduce

This is a historical persisted-state recovery issue; an ordinary Plan toggle and restart is **not** a confirmed fresh-profile reproduction.

1. Use a disposable copy of a data root containing unfinished Graph work that produces a supervisor checkpoint on recovery.
2. The root Session is in Plan mode, or lacks `llmConnectionId` while using the `ai-sdk` backend.
3. Start the production Runtime Host from the unpatched source build.
4. Observe three new `retryable_failed` entries in `agent_graph_supervisor_wake_attempts`, followed by Host startup failure.
5. Start the same copy again: another three failed attempts are recorded.

Repeated with isolated copies of an affected pre-upgrade database; the original application data was not changed. A separate synthetic, credential-free Plan recovery fixture was also developed during earlier investigation. Neither the original database nor credentials will be attached.

### Environment

- Source build: Maka 0.2.0, commit `5846521372d2dd0d3d2d33dc7784dd046dc3f7c8`, built without the local recovery patch.
- OS: macOS 26.5, Apple Silicon.
- Surface: Desktop / production Runtime Host / Agent Graph recovery.
- Runtime used for the latest direct Host verification: Electron 43.4.1's Node 24.18.1.

### Logs, screenshots, or additional context

| Isolated experiment | New wake attempts | New model-call records | Result |
| --- | ---: | ---: | --- |
| Original state, first startup | 3 | 0 | Fails after 503 ms: missing account selection |
| Same root, second startup | 3 | 0 | Fails after 462 ms: missing account selection |
| Bind the existing account in the copy, retain Plan | 3 | 0 | Fails after 920 ms: Plan rejects background execution |
| Remove existing wake/attempt rows, retain unfinished Graph | 3 | 0 | Recovery generates a new wake and fails |
| Fresh Session, missing account identity and Plan, no Graph work | 0 | 0 | Host ready |
| Original state with local recovery patch | 0 | 0 | Host ready |

The two admission errors are:

```text
This Session requires an explicit account selection before it can run.
Background and delegated roots cannot execute while the Session is in Plan mode.
```

These are local admission attempts, not repeated model API requests. The verified behavior is three attempts per startup, recurring on restart; this report does not claim an infinite loop inside one Host process. Both Host timeouts were 60 seconds, well above the observed failure times.

Related but distinct: #3866 / #4626 concern sandbox-answer reconciliation deadlock; #4695 concerns foreground submission before a Plan transition commits.

Automated report prepared and submitted with OpenAI Codex at the human contributor's request. Codex assisted with diagnosis, reproduction, and the proposed fix.