Native V8 array-length crash during active tool-heavy turns and session resume

### Describe the bug

The packaged Linux x64 native binary aborts inside V8 during active, tool-heavy turns as well as while resuming conversations.

The original report attributed this to several concurrent resumes. Further testing disproved that: Herdr automatic restoration was disabled, failed panes were cleared, and an already-running conversation crashed mid-turn while displaying:

```text
Reviewing brief clarity · 29.4 KiB
# Fatal error in , line 0
# Fatal JavaScript invalid array length 0
```

A second active conversation failed similarly while displaying `Shipping Lakebase refactor · 53.7 KiB`. Both ended with SIGILL. These were normal active turns, not startup or bulk restore.

The fatal string maps to V8's `Accessors::ArrayLengthSetter`, where `JSArray::SetLength(..., 0)` returned an exception and V8 called `FATAL`:

https://github.com/v8/v8/blob/main/src/builtins/accessors.cc#L210-L214

### Affected version

GitHub Copilot CLI 1.0.70

### Steps to reproduce the behavior

A minimal deterministic reproduction is not yet available. The recurring observed sequence is:

1. Start or resume a Copilot conversation.
2. Run a long, tool-heavy workflow with many subagents.
3. Start another turn.
4. While Copilot is actively streaming/reviewing the response, the native process aborts with `Fatal JavaScript invalid array length 0` and SIGILL.

Two affected conversation histories were approximately:

- 14.1 MB / 2,482 events / 929 completed tool calls / 23 completed subagents
- 21.3 MB / 3,959 events / approximately 1,500 completed tool calls / 24 started subagents

The final persisted event in each is `assistant.turn_start` without a matching `assistant.turn_end`, confirming the failure occurred mid-turn.

### Expected behavior

Long or tool-heavy conversations should continue normally. If an internal array operation fails, the CLI should surface a recoverable JavaScript error rather than aborting the native process.

### Additional context

- OS: Ubuntu 24.04 under WSL2, Linux `6.6.114.1-microsoft-standard-WSL2`, x86_64
- Terminal: Windows Terminal -> Herdr PTYs
- Shell: zsh
- Memory after the latest crash: 31 GiB total, 28 GiB available, no swap in use
- Copilot's embedded runtime reports Node.js `v24.16.0`
- Kernel logs show repeated SIGILL failures at the same native address
- `app.js` and `index.js` checksums match between the npm platform package and Copilot's update cache
- The npm loader's subsequent `no platform package found` message is misleading; the platform package launched successfully and its child process terminated by signal
- Reinstalling npm replaces 1.0.70 with the same 1.0.70 and does not resolve the failure
- Herdr's `resume_agents_on_restore` setting is not required to trigger this
- Running the packaged JavaScript entrypoint under system Node.js `v24.11.1` passes startup/version and interactive Herdr smoke tests. I am testing this as a temporary workaround, but it has not yet had the same long-duration workload.

Commencez par les points d’entrée JavaScript empaquetés app.js et index.js, puis comparez leur comportement avec le workaround documenté du système Node.js. Reproduisez si possible le workflow long et fortement basé sur les outils d’un tour actif, et capturez l’échec natif. C’est terminé lorsque la charge de travail n’est plus interrompue par le V8 invalid-array-length SIGILL, ou que la CLI affiche à la place une erreur récupérable.

Rédigé par le modèle d'indexation à partir du texte de l'issue.