fix(memtest): extract EFI binary from .deb cache if chroot/boot/ is empty

memtest86+ postinst does not place files in /boot in a live-build chroot
without grub triggers. Added fallback: extract directly from the cached
.deb via dpkg-deb -x, with verbose logging throughout.

Also remove "NVIDIA no MSI-X" from boot menu (premature — root cause unknown).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/builder/config/bootloaders/grub-pc/grub.cfg

@@ -24,11 +24,6 @@ menuentry "EASY-BEE (NVIDIA GSP=off)" {
     initrd  @INITRD_LIVE@
 }
 
-menuentry "EASY-BEE (NVIDIA no MSI-X)" {
-    linux   @KERNEL_LIVE@ @APPEND_LIVE@ nomodeset bee.nvidia.mode=nomsi net.ifnames=0 biosdevname=0 mitigations=off transparent_hugepage=always numa_balancing=disable nowatchdog nosoftlockup
-    initrd  @INITRD_LIVE@
-}
-
 menuentry "EASY-BEE (fail-safe)" {
     linux   @KERNEL_LIVE@ @APPEND_LIVE@ bee.nvidia.mode=gsp-off memtest noapic noapm nodma nomce nolapic nosmp vga=normal net.ifnames=0 biosdevname=0
     initrd  @INITRD_LIVE@

iso/builder/config/hooks/normal/9100-memtest.hook.binary

@@ -2,15 +2,54 @@
 # Copy memtest86+ binaries from chroot /boot into the ISO boot directory
 # so GRUB can chainload them directly (they must be on the ISO filesystem,
 # not inside the squashfs).
+#
+# Primary: copy from chroot/boot/ (populated by package postinst).
+# Fallback: extract directly from the cached .deb if postinst didn't place
+#           the files (happens in chroot environments without grub triggers).
 set -e
 
-echo "memtest: scanning chroot/boot/ for memtest files:"
-ls chroot/boot/memtest* 2>/dev/null || echo "memtest: WARNING: no memtest files found in chroot/boot/"
+MEMTEST_FILES="memtest86+x64.bin memtest86+x64.efi memtest86+ia32.bin memtest86+ia32.efi"
 
-for f in memtest86+x64.bin memtest86+x64.efi memtest86+ia32.bin memtest86+ia32.efi; do
+echo "memtest: scanning chroot/boot/ for memtest files:"
+ls chroot/boot/memtest* 2>/dev/null || echo "memtest: WARNING: no memtest files in chroot/boot/"
+
+# Primary path: copy from chroot/boot/
+for f in ${MEMTEST_FILES}; do
     src="chroot/boot/${f}"
     if [ -f "${src}" ]; then
         cp "${src}" "binary/boot/${f}"
-        echo "memtest: copied ${f} to binary/boot/"
+        echo "memtest: copied ${f} from chroot/boot/"
     fi
 done
+
+# Fallback: if EFI binary still missing, extract from cached .deb
+if [ ! -f "binary/boot/memtest86+x64.efi" ]; then
+    echo "memtest: EFI binary missing — attempting extraction from .deb cache"
+    deb=$(find chroot/var/cache/apt/archives/ chroot/var/lib/apt/lists/ \
+              -name 'memtest86+_*.deb' -o -name 'memtest86+*.deb' 2>/dev/null \
+          | head -1)
+    if [ -z "$deb" ]; then
+        # Also check lb package cache
+        deb=$(find cache/ -name 'memtest86+_*.deb' -o -name 'memtest86+*.deb' 2>/dev/null | head -1)
+    fi
+    if [ -n "$deb" ]; then
+        echo "memtest: extracting from ${deb}"
+        EXTRACT_DIR="$(mktemp -d)"
+        dpkg-deb -x "${deb}" "${EXTRACT_DIR}"
+        echo "memtest: files found in .deb:"
+        find "${EXTRACT_DIR}/boot" -type f 2>/dev/null || echo "  (none in /boot)"
+        for f in ${MEMTEST_FILES}; do
+            src="${EXTRACT_DIR}/boot/${f}"
+            if [ -f "${src}" ]; then
+                cp "${src}" "binary/boot/${f}"
+                echo "memtest: extracted ${f} from .deb"
+            fi
+        done
+        rm -rf "${EXTRACT_DIR}"
+    else
+        echo "memtest: WARNING: no memtest86+ .deb found in cache — memtest will not be available"
+    fi
+fi
+
+echo "memtest: binary/boot/ contents:"
+ls binary/boot/memtest* 2>/dev/null || echo "  (none)"