[Bug]: Windows integrated terminals fail with environment request error after node-pty upgrade

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What happened

On Windows, opening an integrated terminal in T3 Code Nightly shows [terminal] The environment request failed. The terminal panel opens but never shows a usable shell. This persists after updating from 0.0.43-nightly.20260926.2318 to 0.0.43-nightly.20260927.2331 and rebooting.

This blocks running local development hosts from T3 Code. I have to open a separate terminal to start them.

Steps to reproduce

1. Install 0.0.43-nightly.20260927.2331 on Windows.
2. Open a project thread and open an integrated terminal (including a second terminal in the right panel).
3. The panel displays [terminal] The environment request failed.

Diagnosis

The local server trace records successful terminal.trySpawn and terminal.openLocked operations, followed by ws.rpc.terminal.attach ending almost immediately. Terminal output logs contain a PowerShell prompt, so the shell starts but the client cannot display its session.

After the node-pty upgrade in #13748, Windows spawn() can initially return PID 0. The terminal manager stores that value in the snapshot. The client contract accepts a positive PID or null, so it rejects the snapshot and shows the generic environment error. This matches the analysis in #13927.

Fix in progress

#13927 waits for a valid Windows PID before the adapter reports a successful spawn. That PR addresses this exact failure. It is still open and is not in Nightly 0.0.43-nightly.20260927.2331.