fix: heredoc quoting in installer profile.d (boot media not found)

The profile.d script used <<'PROFILE' (single-quoted heredoc) inside
a bash -c '...' single-quoted block. The inner quotes broke the outer
quoting, causing all $ variables to expand to empty at build time.
The for loop checked if [ -f "/archipelago/auto-install.sh" ] instead
of if [ -f "$dev/archipelago/auto-install.sh" ] — never matching.

Fix: use <<PROFILE with \$ escaping (matching .228's working version).
Also adds fallback device scanning if standard mount points are empty,
and fixes same quoting issue in grub-embed.cfg ($root variable).

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

image-recipe/build-auto-installer-iso.sh

@@ -527,10 +527,10 @@ GETTY
 # Auto-start installer via profile.d (runs after auto-login, no getty race)
 # This is the same approach the working Debian Live build used.
 mkdir -p /installer/etc/profile.d
-cat > /installer/etc/profile.d/z99-archipelago-installer.sh <<'PROFILE'
+cat > /installer/etc/profile.d/z99-archipelago-installer.sh <<PROFILE
 #!/bin/bash
 # Auto-start Archipelago installer on login — only run once
-if [ -n "$INSTALLER_STARTED" ]; then
+if [ -n "\$INSTALLER_STARTED" ]; then
     return 0 2>/dev/null || exit 0
 fi
 export INSTALLER_STARTED=1
@@ -545,21 +545,42 @@ echo ""
 
 BOOT_MEDIA=""
 for dev in /run/live/medium /lib/live/mount/medium /run/archiso /cdrom /media/cdrom /mnt/iso; do
-    if [ -f "$dev/archipelago/auto-install.sh" ]; then
+    if [ -f "\$dev/archipelago/auto-install.sh" ]; then
-        BOOT_MEDIA="$dev"
+        BOOT_MEDIA="\$dev"
         break
     fi
 done
 
-if [ -n "$BOOT_MEDIA" ]; then
+# If standard mount points failed, actively find and mount the boot device
-    echo -e "  \033[37mFound installer at: $BOOT_MEDIA\033[0m"
+if [ -z "\$BOOT_MEDIA" ]; then
+    echo -e "  \033[37mSearching for boot device...\033[0m"
+    mkdir -p /run/archiso 2>/dev/null
+    for blk in /dev/sr0 /dev/sd[a-z] /dev/sd[a-z][0-9] /dev/nvme[0-9]n[0-9]p[0-9]; do
+        [ -b "\$blk" ] || continue
+        mount -o ro "\$blk" /run/archiso 2>/dev/null || continue
+        if [ -f /run/archiso/archipelago/auto-install.sh ]; then
+            BOOT_MEDIA="/run/archiso"
+            break
+        fi
+        umount /run/archiso 2>/dev/null
+    done
+fi
+
+if [ -n "\$BOOT_MEDIA" ]; then
+    echo -e "  \033[37mFound installer at: \$BOOT_MEDIA\033[0m"
     echo ""
     echo -e "  Press Enter to install  |  \033[1;37mCtrl+C\033[0m for shell"
     read -s
-    bash "$BOOT_MEDIA/archipelago/auto-install.sh"
+    bash "\$BOOT_MEDIA/archipelago/auto-install.sh"
 else
     echo -e "  \033[37mInstaller not found on boot media.\033[0m"
     echo ""
+    echo -e "  \033[37mDebug info:\033[0m"
+    ls -la /run/live/ 2>/dev/null || echo "    /run/live/ does not exist"
+    mount | grep -E "iso9660|squashfs|overlay" 2>/dev/null
+    echo ""
+    echo -e "  \033[37mTry:  mount /dev/sdX /mnt/iso && bash /mnt/iso/archipelago/auto-install.sh\033[0m"
+    echo ""
 fi
 PROFILE
 chmod +x /installer/etc/profile.d/z99-archipelago-installer.sh
@@ -641,7 +662,7 @@ mksquashfs /installer /output/filesystem.squashfs -comp xz -Xbcj x86 -noappend -
 
 # Build GRUB EFI image with embedded bootstrap config (grub-mkstandalone)
 echo "   [container] Building GRUB EFI image..."
-cat > /tmp/grub-embed.cfg <<'GRUBEMBED'
+cat > /tmp/grub-embed.cfg <<GRUBEMBED
 insmod part_gpt
 insmod fat
 insmod iso9660
@@ -650,7 +671,7 @@ insmod normal
 insmod linux
 insmod all_video
 search --no-floppy --set=root --label ARCHIPELAGO
-set prefix=($root)/boot/grub
+set prefix=(\$root)/boot/grub
 normal
 GRUBEMBED