shellIntegration.executeCommand().read() stream yields no data for commands containing emoji on Windows/PowerShell

**VS Code Version**: 1.104.1
**OS**: Windows 11 (x64)
**Shell**: PowerShell 7 (pwsh 7.x) via ConPTY

## Steps to Reproduce

In a VS Code extension, execute an emoji-containing command via shell integration:

```ts
const execution = terminal.shellIntegration!.executeCommand("echo '❌'")
const stream = execution.read()
for await (const chunk of stream) {
console.log(chunk) // ← never executes
}
console.log("done") // ← never reached