feat: update configs for host+VPS with Intel VirtualHeads and dummy driver

- Host: 20-intel-virtual.conf with Driver intel + VirtualHeads 1
- VPS: xorg-dummy.service + rustdesk-dummy.service for CPU-only
- Updated README with dual setup (host Intel iGPU + VPS dummy)
- Verified: VIRTUAL1 primary after reboot, HDMI1 clone
- Verified: DUMMY0 primary on VPS without GPU

config/vps/rustdesk-dummy.service

@@ -0,0 +1,18 @@
+[Unit]
+Description=RustDesk Server with Dummy Display
+After=xorg-dummy.service
+Requires=xorg-dummy.service
+
+[Service]
+Type=simple
+User=root
+Environment="DISPLAY=:0"
+ExecStartPre=/bin/sleep 5
+ExecStart=/usr/lib/rustdesk/rustdesk --server
+Restart=always
+RestartSec=10
+StandardOutput=append:/var/log/rdtop-rustdesk.log
+StandardError=append:/var/log/rdtop-rustdesk.log
+
+[Install]
+WantedBy=multi-user.target

config/vps/xorg-dummy.service

@@ -0,0 +1,25 @@
+[Unit]
+Description=Xorg Dummy Display for RustDesk VPS
+After=network.target
+
+[Service]
+Type=simple
+User=root
+Environment="DISPLAY=:0"
+ExecStartPre=/bin/mkdir -p /tmp/.X11-unix
+ExecStart=/usr/lib/xorg/Xorg :0 \
+    -nolisten tcp \
+    -nolisten local \
+    -config /etc/X11/xorg.conf.d/99-dummy.conf \
+    +extension GLX \
+    +extension RANDR \
+    +extension RENDER \
+    -novtswitch \
+    -keeptty
+Restart=always
+RestartSec=5
+StandardOutput=append:/var/log/rdtop-xorg.log
+StandardError=append:/var/log/rdtop-xorg.log
+
+[Install]
+WantedBy=multi-user.target

config/x11-host/20-intel-virtual.conf

@@ -0,0 +1,5 @@
+Section "Device"
+    Identifier "Intel Graphics"
+    Driver "intel"
+    Option "VirtualHeads" "1"
+EndSection