Scheduled automation workers never start when the pane shell is PowerShell #507

On Windows with "shell": "pwsh" or "powershell", a scheduled automation never starts its agent. The worker pane receives:

"C:\...\luvus.exe" __automation-worker t1 a1 r1

PowerShell reads a quoted string followed by more tokens as an expression and stops:

ParserError: Unexpected token '__automation-worker' in expression or statement.

The run and its ORCH task then stay running, and nothing reports the failure. With the default overlap: skip, every later occurrence is skipped. An --every 60 automation recorded r1 as running (stuck), then r2 and r3 as skipped with previous run is still active.

Measured

0.14.3 (52def96), Windows 11, PowerShell 7.6, isolated LUVUS_HOME. It fails before any agent starts, so it affects every agent. The same automation runs with "shell": "cmd".

Cause

automation_agent_launch_line (src/app/board.rs) always emits "<exe>" __automation-worker … on Windows. Manual tasks already handle this: manual_agent_runner_line uses & "$env:LUVUS_BIN_PATH" __task-worker for pwsh/powershell and "%LUVUS_BIN_PATH%" __task-worker for cmd.

Proposal

Build the automation launch line per shell in the same way, using the call operator & for PowerShell. Add tests for pwsh, powershell, cmd, and the POSIX form.

I'd like to fix this and will open a PR that closes this issue.