chore(dev): keep the detached dev-server start script

Running "npm run dev" as a tracked agent task gets the process killed
when the runtime cap is reached, which leaves the machine with no dev
server on port 6001. This script starts it with Start-Process so it
survives session churn, and it refuses to start a second server when
the port is already taken.

The older .run-dev.ps1 in the same folder is broken and is replaced by
this one: it invokes the Next binary without its extension, which
PowerShell cannot execute, so node.exe is called explicitly instead.

Workflow/.start-dev-detached.ps1

@@ -0,0 +1,30 @@
+# Start the Workflow dev server fully detached from the agent session.
+#
+# WHY THIS FILE EXISTS
+#   Running "npm run dev" as a tracked background task gets the process
+#   killed when the runtime 3600000ms cap is reached (about 1 hour).
+#   Start-Process detaches it, so it survives session churn.
+#
+# NOTE: the older .run-dev.ps1 in this folder is broken. It calls
+#   & '.\node_modules\next\dist\bin\next'
+#   but that path has no extension, so PowerShell cannot execute it.
+#   node.exe must be invoked explicitly, which is what this script does.
+#
+# Usage:  powershell -NoProfile -ExecutionPolicy Bypass -File .start-dev-detached.ps1
+
+$ErrorActionPreference = 'Continue'
+
+$root    = 'C:\Users\SJ\.minimax-agent\projects\Workflow'
+$logFile = Join-Path $root '.dev-detached.log'
+
+# Do not start a second server if one is already listening on 6001.
+$existing = (Get-NetTCPConnection -LocalPort 6001 -State Listen -ErrorAction SilentlyContinue).OwningProcess
+if ($existing) {
+    Write-Host "Port 6001 already in use by PID $existing. Nothing to do."
+    exit 0
+}
+
+$proc = Start-Process -FilePath 'node.exe' -ArgumentList 'node_modules\next\dist\bin\next','dev','-p','6001' -WorkingDirectory $root -WindowStyle Hidden -RedirectStandardOutput $logFile -RedirectStandardError "$logFile.err" -PassThru
+
+Write-Host "Workflow dev server started detached (PID $($proc.Id))."
+Write-Host "Log: $logFile"