Displays managers & zram menu

- LightDM Overhaul: Rewrote `install_lightdm()` logic to verify both lightdm and lightdm-gtk-gtk-greeter-settings. Now installs the trio in a single command if missing, skipping only when fully present. Added "Enable autologin" option modifying `/etc/lightdm/lightdm.conf` with robust `sed` patterns for `SUDO_USER`. Fixed missing `debconf-set-selections` to ensure LightDM is set as default during installation.
- GDM3 Implementation: Created a new sub-menu in `modules/desktop_display.sh` allowing independent installation of GDM3, User List toggle (hide/show), Autologin configuration via `/etc/gdm3/daemon.conf`, and conditional "Force Enable Wayland on NVIDIA" for Debian 12/13 using udev symlinks.
- SDDM Integration: Added SDDM as option 3 in the Display Manager menu. Implemented automatic session detection (Wayland > X11) to populate `/etc/sddm.conf.d/autologin.conf` without user input, defaulting to plasmawayland, lxqt-wayland, or generic fallbacks.
- greetd support: Added conditional support for Debian 12 and 13 only. Implemented sub-menu with base install, recommended `tuigreet` (with backports handling for Bookworm), and other manual setup options (`gtkgreet`, `nwg-hello`, `wlgreet`) exclusive to Trixie. 
- ZRAM UX Improvements: Updated descriptions in `modules/zram.sh` to explicitly mention I/O reduction and responsiveness benefits for low-RAM systems (e.g., 4GB). Cleaned up compression algorithm labels (`lz4`, `zstd`) to remove redundancy in menu values.
- General Code Quality: Standardized all user-facing messages to English across modules. Ensured independent package installation checks prevent script abortion if one DM fails, while maintaining strict error handling for system configurations.
- update docs and readme

modules/zram.sh

@@ -12,17 +12,11 @@ install_zram() {
     local half_ram_mb=$(( ((RAM_KB / 1024 / 1024 + 1) / 2) * 1024 ))
 
     local algo
-    algo=$(_menu "ZRAM Compression" \
-        "ZRAM compresses a portion of RAM into compressed swap,\
- effectively increasing available memory.
-
-Useful for systems with limited RAM or when you need
-more swap space without disk writes.
-
-Choose compression algorithm:" \
+    algo=$(_menu "ZRAM Configuration" \
+        "ZRAM creates a compressed block device in RAM to use as swap. This reduces disk I/O and can significantly improve responsiveness on systems with limited memory (e.g., 4GB RAM or less), at the cost of a small amount of CPU usage." \
         $TUI_ALTO $TUI_ANCHO $TUI_ALTO_LISTA \
-        "lz4"  "Fastest, low CPU (recommended)" \
-        "zstd" "Better ratio, more CPU")
+        "lz4"  "Fastest compression/decompression. Lowest CPU overhead. (Default)" \
+        "zstd" "Higher compression ratio. Saves slightly more memory but uses more CPU.")
 
     if [ -z "$algo" ]; then
         echo "ZRAM configuration cancelled."