Fix auto-installer disk size calculation arithmetic error

- Fixed lsblk output parsing that was causing syntax error at line 138
- Added head -1 and tr -d to handle multiple lines or whitespace in lsblk output
- Added numeric validation to prevent arithmetic errors
- Applied same fix to both disk detection functions (lines 138 and 244)

Auto-installer now runs without syntax errors and properly detects disk sizes.
Autologin system fully operational - console passwordless, SSH requires password.

config/includes.chroot/usr/local/bin/auto-installer.sh

@@ -134,7 +134,11 @@ detect_target_disk() {
         fi
         
         # Skip if disk is too small (less than 4GB)
-        local size_bytes=$(lsblk -rbno SIZE "$disk" 2>/dev/null || echo 0)
+        local size_bytes=$(lsblk -rbno SIZE "$disk" 2>/dev/null | head -1 | tr -d ' ' || echo 0)
+        # Ensure size_bytes is a valid number
+        if ! [[ "$size_bytes" =~ ^[0-9]+$ ]]; then
+            size_bytes=0
+        fi
         local size_gb=$((size_bytes / 1024 / 1024 / 1024))
         
         if [ "$size_gb" -lt 4 ]; then
@@ -241,7 +245,11 @@ confirm_installation() {
     print_status "  Target: $TARGET_DISK (will be completely erased)"
     
     # Get disk size for display
-    local size_bytes=$(lsblk -rbno SIZE "$TARGET_DISK" 2>/dev/null || echo 0)
+    local size_bytes=$(lsblk -rbno SIZE "$TARGET_DISK" 2>/dev/null | head -1 | tr -d ' ' || echo 0)
+    # Ensure size_bytes is a valid number
+    if ! [[ "$size_bytes" =~ ^[0-9]+$ ]]; then
+        size_bytes=0
+    fi
     local size_gb=$((size_bytes / 1024 / 1024 / 1024))
     print_status "  Target size: ${size_gb} GB"