Security hardening & DRY refactoring

- Fixed command injection in desktop_display.sh by converting word-splitting loops to safe array-based iteration for LightDM/GDM3 configuration and XFCE package installation.
- Added symlink detection guard before repository file operations in repos.sh to prevent TOCTOU attacks during restore_previous_repos().
- Hardened SUDO_USER resolution with awk validation against /etc/passwd to prevent root fallback and ensure real login users are targeted for sudoers configuration.
- Implemented algorithm (lz4/zstd) and size validation before ZRAM configuration writes in zram.sh to reject invalid inputs.
- Protected grep MemTotal read from /proc/meminfo with 2>/dev/null and default assignment under set -u.
- Added || true guards around apt-cache madison pipelines in firmware.sh, kernel.sh, gpu.sh, and utils.sh to prevent pipefail aborts when backports unavailable.
- Wrapped whiptail installation in if/else blocks to allow offline error messages instead of script termination under set -e.
- Fixed grep -c output duplication in swap.sh with proper || true pattern and default variable assignment.
- Replaced unquoted $cleaned loops with array conversion using while read for secure package iteration across gaming, desktop_display, firmware, and kernel modules.
- Anchored sed regex patterns to space-delimited "main" components to prevent mirror URL corruption in sources.list editing.
- Escaped % characters in _msg() function before passing to whiptail to prevent printf format interpretation crashes.
- Consolidated package version helpers into canonical wrappers: _get_pkg_version, _get_installed_version, _get_backports_version for consistent apt/dpkg queries.
- Created _install_if_missing() and _install_pkg() with proper error handling that respects set -e while providing user feedback on installation failures.
- Removed 6 dead code functions (~51 lines): check_system_time, sync_system_time, get_cpu_summary, get_ram_summary, pkg_versions, get_backports_kernel_version.
- Added detect_displayserver and detect_audio_server to refresh_system_state() for complete state refresh when returning from menus.
- Enhanced _on_interrupt() trap handler to kill lingering apt/dpkg child processes and clean /tmp/debianito.* temporary files on Ctrl+C or TERM.
- Improved restore_previous_repos() with manifest-based backup verification (.backed_up_* markers) to prevent destructive repository file deletion.
- Added mktemp usage for secure temporary deb file downloads in nvidia.sh, heroic.sh, and tools.sh to eliminate TOCTOU vulnerabilities in /tmp.
- Fixed Bluetooth USB dongle misclassification as WiFi devices by excluding "bluetooth" strings from USB_WIFI_DEVS detection in firmware.sh.
- Properly utilized the need array for selective package installation in internet.sh instead of hardcoding full package list.
- Corrected fwupdmgr duplicate execution and grep false positives in system.sh with strict pattern matching for available updates.
- update docs and added quickstart guide

modules/bluetooth.sh

@@ -19,6 +19,7 @@ _install_bluetooth_stack() {
         return
     fi
 
+    local stack_failed=false
     if is_installed bluez; then
         echo "  → Bluetooth stack already installed."
         service_enable_only=true
@@ -30,7 +31,10 @@ _install_bluetooth_stack() {
         ! is_installed bluez-tools  && bt_pkgs+=(bluez-tools)
         ! is_installed bluez-obexd  && bt_pkgs+=(bluez-obexd)
         if [ ${#bt_pkgs[@]} -gt 0 ]; then
-            _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y ${bt_pkgs[*]}" "Installing Bluetooth stack..."
+            if ! _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y ${bt_pkgs[*]}" "Installing Bluetooth stack..."; then
+                _msg_red "Bluetooth" "Failed to install the Bluetooth stack."
+                stack_failed=true
+            fi
         fi
     fi
 
@@ -44,11 +48,21 @@ _install_bluetooth_stack() {
     case "${DESKTOP_ENV:-other}" in
         kde)
             if ! is_installed bluedevil; then
-                _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y bluedevil" "Installing bluedevil..."
+                if ! _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y bluedevil" "Installing bluedevil..."; then
+                    _msg_red "Bluetooth" "Failed to install bluedevil."
+                fi
             fi
             if [ "${AUDIO_SERVER:-}" = "pipewire" ]; then
-                ! is_installed pipewire-pulse && _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y pipewire-pulse" "Installing pipewire-pulse..."
-                ! is_installed wireplumber && _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y wireplumber" "Installing wireplumber..."
+                if ! is_installed pipewire-pulse; then
+                    if ! _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y pipewire-pulse" "Installing pipewire-pulse..."; then
+                        _msg_red "Bluetooth" "Failed to install pipewire-pulse."
+                    fi
+                fi
+                if ! is_installed wireplumber; then
+                    if ! _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y wireplumber" "Installing wireplumber..."; then
+                        _msg_red "Bluetooth" "Failed to install wireplumber."
+                    fi
+                fi
             fi
             ;;
         gnome)
@@ -56,7 +70,9 @@ _install_bluetooth_stack() {
             ;;
         xfce|other)
             if ! is_installed blueman; then
-                _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y blueman" "Installing blueman..."
+                if ! _run_cmd "Bluetooth" "sudo DEBIAN_FRONTEND=noninteractive apt install -y blueman" "Installing blueman..."; then
+                    _msg_red "Bluetooth" "Failed to install blueman."
+                fi
             fi
             ;;
     esac
@@ -68,5 +84,9 @@ _install_bluetooth_stack() {
         sudo systemctl start bluetooth 2>/dev/null || true
     fi
 
-    _msg "Bluetooth Setup" "Bluetooth stack installed.\n\nA session restart or reboot is\nrecommended to load the desktop\napplets and tray icons." 10 60
+    if $stack_failed; then
+        _msg_red "Bluetooth Setup" "Bluetooth setup finished with errors.\n\nThe stack may be incomplete.\nA session restart or reboot is\nrecommended to load the desktop\napplets and tray icons." 10 60
+    else
+        _msg "Bluetooth Setup" "Bluetooth stack installed.\n\nA session restart or reboot is\nrecommended to load the desktop\napplets and tray icons." 10 60
+    fi
 }