vmix CLI, laptop images, SDL display

CLI (nix run .#):
- `vmix build` and `vmix copy` subcommands
- --image, --generalize key=val, --to-disk, --to-remote-disk
- SDL display auto-detected via DISPLAY temp file passthrough
- --print-build-logs for visible build progress
- -S 4k sparse writes for faster disk copy

Images:
- win10.laptop and win11.laptop bundles (no VirtIO, keeps defender/hibernation)
- templates.bundles.laptop shared template list
- win11 adds reg.disableUCPD on top

Build improvements:
- consistent === vmix: === log prefixes
- SDL display via /tmp/.vmix-display-$$ temp file

Env helpers:
- .env-export-vmix-cli-local: vmix alias for local flake

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/images/windows/helpers/customizeImage.nix

@@ -62,6 +62,8 @@
 
     cdromArgs = lib.concatMapStringsSep " \\\n      " (cd: "-drive file=${cd},media=cdrom,readonly=on") cdroms;
 
+    displayArg = if vncDisplay != null then "-vnc ${vncDisplay}" else null;
+
     auditBootCommands = lib.optionalString hasAuditScript ''
 
       echo "=== vmix: injecting audit script (${name}) ==="
@@ -77,9 +79,19 @@
       cp ${pkgs.OVMF.fd}/FV/OVMF_VARS.fd vars.fd
       chmod +w vars.fd
 
-      echo "=== vmix: booting Audit Mode for ${name} (VNC: ${if vncDisplay != null then vncDisplay else "disabled"}) ==="
+      VMIX_DISPLAY="-nographic"
+      ${lib.optionalString (displayArg != null) ''VMIX_DISPLAY="${displayArg}"''}
+      ${lib.optionalString (displayArg == null) ''
+        VMIX_DF=$(ls -t /tmp/.vmix-display-* 2>/dev/null | head -1)
+        if [ -n "$VMIX_DF" ]; then
+          export DISPLAY=$(cat "$VMIX_DF")
+          VMIX_DISPLAY="-display sdl"
+        fi
+      ''}
+
+      echo "=== vmix: booting Audit Mode for ${name} ==="
       timeout 1800 qemu-system-x86_64 \
-        ${if vncDisplay != null then "-vnc ${vncDisplay}" else "-nographic"} \
+        $VMIX_DISPLAY \
         -accel kvm \
         -m ${toString memSize} \
         -smp ${toString smp} \