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/zram.sh

@@ -9,7 +9,7 @@ install_zram() {
         return 1
     fi
 
-    local half_ram_mb=$((RAM_KB / 2 / 1024))
+    local half_ram_mb=$(( ((RAM_KB / 1024 / 1024 + 1) / 2) * 1024 ))
 
     local algo
     algo=$(whiptail --title "ZRAM Compression" --menu \
@@ -31,12 +31,12 @@ Choose compression algorithm:" \
     fi
 
     local zram_size
-    if _confirm "ZRAM Size" "Use 50% of RAM for ZRAM? (${half_ram_mb} MB out of ${RAM_SUMMARY})"; then
+    if _confirm "ZRAM Size" "Use recommended size for ZRAM? (${half_ram_mb} MB out of ${RAM_SUMMARY})"; then
         zram_size=$half_ram_mb
     else
         zram_size=$(whiptail --title "ZRAM Size" --inputbox \
             "Enter ZRAM size in MB:" 8 60 "$half_ram_mb" 3>&1 1>&2 2>&3)
-        if [ -z "$zram_size" ] || ! [[ "$zram_size" =~ ^[0-9]+$ ]]; then
+        if [ -z "$zram_size" ] || ! [[ "$zram_size" =~ ^[0-9]+$ ]] || [ "$zram_size" -eq 0 ]; then
             echo "ZRAM configuration cancelled."
             return 0
         fi