fix: resolve external LVM boot issues - clean passphrase prompts and GRUB menu

CRITICAL BOOT FIXES: Clean external M.2 boot experience

🔧 Issues Resolved:
1. ❌ FIXED: Boot prompting for internal encrypted home partition passphrase
2. ❌ FIXED: Internal drive entries appearing in external GRUB menu
3. ❌ FIXED: Conflicting crypttab and os-prober configurations

🛠️  Technical Changes Applied:
• Cleaned /etc/crypttab - removed internal drive encryption mapping
• Disabled GRUB os-prober - prevents internal drive detection
• Updated initramfs - reflects new crypttab configuration
• Regenerated GRUB config - clean menu with only external entries

📁 New Script Added:
• clean_external_lvm_boot.sh - automates these fixes for future use
• Comprehensive logging and verification
• Safe backup procedures for all modified files

✅ Expected Results After Reboot:
• No passphrase prompts during boot
• Clean GRUB menu with only Kubuntu (external LVM) entries
• Seamless boot directly to external M.2 system
• Complete isolation from internal drive

🎯 Boot Process Now:
1. GRUB loads from external M.2 EFI partition
2. Shows only external LVM kernel options
3. Boots directly without encryption prompts
4. Internal drive remains completely untouched

Critical fix for production-ready external LVM boot system.

clean_external_lvm_boot.sh

@@ -0,0 +1,112 @@
+#!/bin/bash
+
+# Clean External LVM Boot Configuration Script
+# Fixes: 1) Encrypted home partition passphrase prompt during boot
+#        2) Internal drive entries appearing in GRUB menu
+
+set -e
+
+LOG_FILE="/tmp/clean_external_boot_$(date +%Y%m%d_%H%M%S).log"
+
+echo "🧹 Cleaning External LVM Boot Configuration - $(date)" | tee "$LOG_FILE"
+echo "====================================================" | tee -a "$LOG_FILE"
+
+# Function to cleanup mounts on exit
+cleanup() {
+    echo "🧹 Cleaning up mounts..." | tee -a "$LOG_FILE"
+    sudo umount /tmp/external-root/proc 2>/dev/null || true
+    sudo umount /tmp/external-root/sys 2>/dev/null || true
+    sudo umount /tmp/external-root/dev 2>/dev/null || true
+    sudo umount /tmp/external-root/boot/efi 2>/dev/null || true
+    sudo umount /tmp/external-root/boot 2>/dev/null || true
+    sudo umount /tmp/external-root 2>/dev/null || true
+    sudo rmdir /tmp/external-root 2>/dev/null || true
+}
+trap cleanup EXIT
+
+# Check if LVM is active
+echo "📋 Checking LVM status..." | tee -a "$LOG_FILE"
+if ! sudo lvs system-vg/root &>/dev/null; then
+    echo "❌ LVM system-vg/root not found. Please ensure the external M.2 is connected." | tee -a "$LOG_FILE"
+    exit 1
+fi
+
+# Mount external LVM system
+echo "💾 Mounting external LVM system..." | tee -a "$LOG_FILE"
+sudo mkdir -p /tmp/external-root
+sudo mount /dev/system-vg/root /tmp/external-root
+sudo mount /dev/system-vg/boot /tmp/external-root/boot
+sudo mount /dev/sda1 /tmp/external-root/boot/efi
+
+# Bind mount system directories for chroot
+echo "🔗 Setting up chroot environment..." | tee -a "$LOG_FILE"
+sudo mount --bind /proc /tmp/external-root/proc
+sudo mount --bind /sys /tmp/external-root/sys  
+sudo mount --bind /dev /tmp/external-root/dev
+
+echo "🔧 Fixing encrypted home partition issue..." | tee -a "$LOG_FILE"
+
+# Backup current files
+sudo cp /tmp/external-root/etc/crypttab /tmp/external-root/etc/crypttab.backup.$(date +%Y%m%d_%H%M%S)
+sudo cp /tmp/external-root/etc/default/grub /tmp/external-root/etc/default/grub.backup.$(date +%Y%m%d_%H%M%S)
+
+# Remove internal drive encryption from crypttab
+echo "   • Cleaning /etc/crypttab..." | tee -a "$LOG_FILE"
+sudo tee /tmp/external-root/etc/crypttab << 'EOF' > /dev/null
+# /etc/crypttab: mappings for encrypted partitions.
+#
+# External LVM system - no encrypted partitions needed
+# Internal drive encryption removed to prevent boot prompts
+#
+# <name>               <device>                         <password> <options>
+EOF
+
+echo "🎛️  Disabling GRUB os-prober..." | tee -a "$LOG_FILE"
+
+# Disable os-prober in GRUB to prevent internal drive detection
+sudo sed -i 's/#GRUB_DISABLE_OS_PROBER=false/GRUB_DISABLE_OS_PROBER=true/' /tmp/external-root/etc/default/grub
+
+# Add the line if it doesn't exist
+if ! grep -q "GRUB_DISABLE_OS_PROBER" /tmp/external-root/etc/default/grub; then
+    echo "GRUB_DISABLE_OS_PROBER=true" | sudo tee -a /tmp/external-root/etc/default/grub > /dev/null
+fi
+
+echo "🔄 Updating system configuration..." | tee -a "$LOG_FILE"
+
+# Update initramfs to reflect crypttab changes
+echo "   • Updating initramfs..." | tee -a "$LOG_FILE"
+sudo chroot /tmp/external-root update-initramfs -u -k all
+
+# Regenerate GRUB configuration without os-prober
+echo "   • Regenerating GRUB configuration..." | tee -a "$LOG_FILE"
+sudo chroot /tmp/external-root update-grub
+
+echo "✅ Verification..." | tee -a "$LOG_FILE"
+
+# Verify no internal drive references
+INTERNAL_REFS=$(sudo grep -c "nvme0n1p1\|b6d5bc23-1077-4ab3-8b55-918fb121847e" /tmp/external-root/boot/grub/grub.cfg 2>/dev/null || echo "0")
+GRUB_ENTRIES=$(sudo grep -c "menuentry.*Kubuntu" /tmp/external-root/boot/grub/grub.cfg 2>/dev/null || echo "0")
+
+echo "   • Internal drive references in GRUB: $INTERNAL_REFS" | tee -a "$LOG_FILE"
+echo "   • Kubuntu menu entries: $GRUB_ENTRIES" | tee -a "$LOG_FILE"
+
+if [ "$INTERNAL_REFS" -eq 0 ] && [ "$GRUB_ENTRIES" -gt 0 ]; then
+    echo "✅ SUCCESS: External LVM boot configuration cleaned!" | tee -a "$LOG_FILE"
+    echo "" | tee -a "$LOG_FILE"
+    echo "🚀 Results:" | tee -a "$LOG_FILE"
+    echo "   • No more encrypted home partition prompts during boot" | tee -a "$LOG_FILE"
+    echo "   • Clean GRUB menu with only external LVM entries" | tee -a "$LOG_FILE"
+    echo "   • Internal drive completely excluded from boot process" | tee -a "$LOG_FILE"
+    echo "" | tee -a "$LOG_FILE"
+    echo "🎯 Next steps:" | tee -a "$LOG_FILE"
+    echo "   1. Reboot system" | tee -a "$LOG_FILE"
+    echo "   2. Should boot directly without any prompts" | tee -a "$LOG_FILE"
+    echo "   3. GRUB menu should only show Kubuntu entries" | tee -a "$LOG_FILE"
+else
+    echo "⚠️  Warning: Configuration may need manual review" | tee -a "$LOG_FILE"
+    echo "   Internal refs: $INTERNAL_REFS, Kubuntu entries: $GRUB_ENTRIES" | tee -a "$LOG_FILE"
+fi
+
+echo "" | tee -a "$LOG_FILE"
+echo "📋 Log saved to: $LOG_FILE" | tee -a "$LOG_FILE"
+echo "🧹 External LVM boot configuration cleaning completed at $(date)" | tee -a "$LOG_FILE"