feat: replace serial automation with resident TCP agent

.qemu/run.ps1

@@ -4,26 +4,21 @@ $ErrorActionPreference = 'Stop'
 $qemu = Get-Command qemu-system-i386.exe -ErrorAction Stop
 $node = Get-Command node.exe -ErrorAction Stop
 $disk = Join-Path $PSScriptRoot 'freedos.qcow2'
-$share = Join-Path $PSScriptRoot 'share'
-$relay = Join-Path $PSScriptRoot 'serial-relay.mjs'
-
-# QEMU's FAT-directory drive is a convenient exchange volume, but it is not a
-# reliable live-sync mechanism. Restart QEMU after host-side source changes.
-New-Item -ItemType Directory -Force -Path $share | Out-Null
+$relay = Join-Path $PSScriptRoot 'tcp-agent-relay.mjs'
 
 if (-not (Test-Path -LiteralPath $disk)) {
     throw "Missing $disk. Run .qemu\\setup.ps1, then .qemu\\install.ps1."
 }
 
-$relayListening = Get-NetTCPConnection -State Listen -LocalPort 5556 -ErrorAction SilentlyContinue
+$relayListening = Get-NetTCPConnection -State Listen -LocalPort 5558 -ErrorAction SilentlyContinue
 if (-not $relayListening) {
     Start-Process -FilePath $node.Source -ArgumentList @($relay) -WorkingDirectory $PSScriptRoot -WindowStyle Hidden
     $deadline = [DateTime]::UtcNow.AddSeconds(5)
     do {
         Start-Sleep -Milliseconds 100
-        $relayListening = Get-NetTCPConnection -State Listen -LocalPort 5556 -ErrorAction SilentlyContinue
+        $relayListening = Get-NetTCPConnection -State Listen -LocalPort 5558 -ErrorAction SilentlyContinue
     } while (-not $relayListening -and [DateTime]::UtcNow -lt $deadline)
-    if (-not $relayListening) { throw 'Serial relay did not start.' }
+    if (-not $relayListening) { throw 'TCP agent relay did not start.' }
 }
 
 $monitorListening = Get-NetTCPConnection -State Listen -LocalPort 4444 -ErrorAction SilentlyContinue
@@ -36,9 +31,7 @@ if ($monitorListening) {
     -smp 1 `
     -m 64 `
     -drive "file=$disk,format=qcow2,if=ide,index=0,media=disk" `
-    -hdb "fat:rw:$share" `
     -nic user,model=ne2k_isa `
     -monitor "tcp:127.0.0.1:4444,server=on,wait=off" `
-    -serial "tcp:127.0.0.1:5556" `
     -boot order=c `
     -display default