fix backports and system modules

- Refactored `is_backports_enabled()` to dynamically detect backports using `DEBIAN_CODENAME` instead of hardcoded strings, improving script portability.
- Added support for standalone classic backports files (`/etc/apt/sources.list.d/debian-backports.list`) and deb822 format (`*.sources`) to ensure consistent detection across different repository configurations.
- Resolved Mesa and Kernel backports detection bugs, ensuring correct dialogue prompts and preventing false error messages during installation.
- Implemented smart rounding for zram memory allocation to the nearest Gigabyte for optimized performance.
- Enhanced Whiptail manual input validation for zram to block empty, non-numeric, or zero values.
- Introduced a dedicated `software_centers.sh` module for the modular and clean installation of GNOME Software and Plasma Discover.
- Added smart desktop environment detection (GTK/QT) to automatically suggest and install the optimal software center.
- Implemented a two-phase installation flow for software centers (Base Store -> Optional Flatpak support) with static consistency warnings based on the detected desktop environment.
- update README.md

modules/extras/system/software_centers.sh

@@ -0,0 +1,40 @@
+# software_centers.sh — Standalone Software Center installer
+
+_cat_software_centers() {
+    local de_type
+    de_type=$(_detect_desktop_type)
+    local sc_choice
+    sc_choice=$(whiptail --title "Software Centers" --menu \
+        "Choose a software store to install:" 12 65 2 \
+        "gnome-software"   "Software Center for GNOME" \
+        "plasma-discover"  "Software manager for Plasma" \
+        3>&1 1>&2 2>&3)
+    [ -z "$sc_choice" ] && return
+
+    if { [ "$de_type" = "qt" ] && [ "$sc_choice" = "gnome-software" ]; } || \
+       { [ "$de_type" = "gtk" ] && [ "$sc_choice" = "plasma-discover" ]; }; then
+        _msg "Warning" "Warning: This store requires extra background libraries \
+and may look visually inconsistent with your current desktop environment."
+        ! _confirm "Continue?" "Install anyway?" && return
+    fi
+
+    _run_cmd "Install" "sudo apt install -y $sc_choice" "Installing ${sc_choice}..."
+
+    if _confirm "Flatpak Support" "Do you want to enable Flatpak support for this software center?"; then
+        local bpkg
+        if [ "$sc_choice" = "gnome-software" ]; then
+            bpkg="gnome-software-plugin-flatpak"
+        else
+            bpkg="plasma-discover-backend-flatpak"
+        fi
+        if ! is_installed "flatpak"; then
+            _run_cmd "Flatpak" "sudo apt install -y flatpak" "Installing Flatpak..."
+        fi
+        _run_cmd "Plugin" "sudo apt install -y $bpkg" "Installing $bpkg..."
+        flatpak remote-add --if-not-exists flathub \
+            https://dl.flathub.org/repo/flathub.flatpakrepo
+        echo "Flathub repository added."
+    fi
+
+    echo -e "${GREEN}Software store installed.${NC}"
+}

modules/extras/system/system.sh

@@ -1,6 +1,21 @@
 #!/usr/bin/env bash
 # system.sh — System Tools (extrepo moved here from Dev & Servers)
 
+_detect_desktop_type() {
+    local desktop
+    desktop="${XDG_CURRENT_DESKTOP:-${DESKTOP_SESSION:-}}"
+    desktop="${desktop,,}"
+
+    case "$desktop" in
+        *kde*|*lxqt*|*razor*|*plasma*)
+            echo "qt"; return ;;
+        *gnome*|*xfce*|*cinnamon*|*mate*|*lxde*|*budgie*|*sway*|*hyprland*|*i3*|*bspwm*|*openbox*|*fluxbox*)
+            echo "gtk"; return ;;
+    esac
+
+    echo "gtk"
+}
+
 _cat_general() {
     local headless=false
     _is_headless && headless=true
@@ -113,19 +128,38 @@ _cat_general() {
             flatpak)
                 if ! is_installed "flatpak"; then
                     _run_cmd "Flatpak" "sudo apt install -y flatpak" "Installing Flatpak..."
-                    if command -v plasma-discover &>/dev/null; then
-                        _run_cmd "Flatpak" "sudo apt install -y plasma-discover-backend-flatpak" "Installing Flatpak backend..."
-                        echo "Flatpak backend for Discover installed."
-                    elif command -v gnome-software &>/dev/null; then
-                        _run_cmd "Flatpak" "sudo apt install -y gnome-software-plugin-flatpak" "Installing Flatpak plugin..."
-                        echo "Flatpak plugin for GNOME Software installed."
-                    fi
                 else
                     echo "Flatpak already installed."
                 fi
                 flatpak remote-add --if-not-exists flathub \
                     https://dl.flathub.org/repo/flathub.flatpakrepo
                 echo "Flathub repository added."
+
+                if command -v plasma-discover &>/dev/null; then
+                    if ! is_installed "plasma-discover-backend-flatpak" 2>/dev/null; then
+                        if _confirm "Discover Backend" "Install Flatpak backend for Plasma Discover?"; then
+                            _run_cmd "Backend" "sudo apt install -y plasma-discover-backend-flatpak" "Installing Flatpak backend..."
+                        fi
+                    fi
+                elif command -v gnome-software &>/dev/null; then
+                    if ! is_installed "gnome-software-plugin-flatpak" 2>/dev/null; then
+                        if _confirm "GNOME Plugin" "Install Flatpak plugin for GNOME Software?"; then
+                            _run_cmd "Plugin" "sudo apt install -y gnome-software-plugin-flatpak" "Installing Flatpak plugin..."
+                        fi
+                    fi
+                else
+                    local de_type
+                    de_type=$(_detect_desktop_type)
+                    if [ "$de_type" = "qt" ]; then
+                        if _confirm "Software Center" "Install Plasma Discover for Flatpak management?"; then
+                            _run_cmd "Discover" "sudo apt install -y plasma-discover plasma-discover-backend-flatpak" "Installing Discover..."
+                        fi
+                    else
+                        if _confirm "Software Center" "Install GNOME Software for Flatpak management?"; then
+                            _run_cmd "GNOME Software" "sudo apt install -y gnome-software gnome-software-plugin-flatpak" "Installing GNOME Software..."
+                        fi
+                    fi
+                fi
                 echo -e "${GREEN}A reboot is recommended.${NC}"
                 ;;
             fwupd)
@@ -191,3 +225,4 @@ _cat_general() {
 
     echo -e "${GREEN}System tools installed.${NC}"
 }
+