Read port forwards from per-VM forwards.conf files

A QEMU config file section cannot hold more than one hostfwd entry, so
the forwards move out of the ini files into qemu/<vm>/forwards.conf, one
"LABEL HOST_PORT GUEST_PORT" rule per line. The new vmforwards.py parses
them, skips rules whose host port is taken and builds the -netdev
argument, which every launcher now passes instead of relying on a
netdev section in the ini or on -nic.

The ini files move to qemu/<vm>/config.ini and qemu/<vm>/<os>-<arch>.ini.
The *_SSH_PORT / *_RDP_PORT variables and --rdp-port / --ssh-port still
replace the host port of the SSH and RDP rules.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

qemu/windows11/config.ini

@@ -0,0 +1,83 @@
+# QEMU configuration for the Windows 11 virtual machine. The accelerators and machine type
+# are in <os>-<arch>.ini (os is linux or darwin), which QEMU reads after
+# this file.
+#
+# run-windows11.py fills in the file path placeholders below, writes the result
+# to <state dir>/qemu.ini and passes it to QEMU with -readconfig. Options that
+# have no -readconfig equivalent (-cpu, -display) and the installation media
+# attached by --install-from-iso are still added by the launcher.
+
+[name]
+  guest = "windows11"
+
+[memory]
+  size = "8G"
+
+[smp-opts]
+  cpus = "8"
+
+# UEFI firmware: read-only code and the per-VM variable store.
+[drive "pflash0"]
+  if = "pflash"
+  format = "raw"
+  readonly = "on"
+  file = "${uefi_code}"
+
+[drive "pflash1"]
+  if = "pflash"
+  format = "raw"
+  file = "${uefi_vars}"
+
+# System disk image; the device that exposes it (and the NIC, which is
+# attached to the user-mode network "net0" that the launcher defines with
+# -netdev from qemu/windows11/forwards.conf because a config file section cannot hold
+# more than one hostfwd) is in the architecture file.
+[drive "system_disk"]
+  if = "none"
+  format = "qcow2"
+  file = "${disk_image}"
+
+# Host/guest clipboard integration through the SPICE vdagent channel.
+[device "virtio_serial"]
+  driver = "virtio-serial-pci"
+
+[chardev "vdagent"]
+  backend = "qemu-vdagent"
+  name = "vdagent"
+  clipboard = "on"
+  mouse = "off"
+
+[device "vdagent-port"]
+  driver = "virtserialport"
+  chardev = "vdagent"
+  name = "com.redhat.spice.0"
+
+# Register the USB tablet after vdagent so QEMU selects it as the active pointer.
+[device "usb_controller"]
+  driver = "qemu-xhci"
+
+[device "tablet0"]
+  driver = "usb-tablet"
+  bus = "usb_controller.0"
+
+# QEMU Guest Agent and the QEMU monitor, both on sockets in the state directory.
+[chardev "qga"]
+  backend = "socket"
+  path = "${guest_agent_socket}"
+  server = "on"
+  wait = "off"
+
+[device "qga-port"]
+  driver = "virtserialport"
+  chardev = "qga"
+  name = "org.qemu.guest_agent.0"
+
+[chardev "monitor"]
+  backend = "socket"
+  path = "${monitor_socket}"
+  server = "on"
+  wait = "off"
+
+[mon "monitor0"]
+  chardev = "monitor"
+  mode = "readline"