Switch desktop from Budgie to KDE Plasma; OpenRGB support and misc packages

Budgie's Wayland session had been broken; Plasma 6 replaces it with SDDM
still handling the Wayland greeter. Since the KDE apps in apps.nix were
already installed as GTK/MATE replacements, Budgie's exclude-package list
is no longer needed under native Plasma.

Also: OpenRGB service + udev rule, RTL-SDR/system tweaks, lmms, qemu,
qt5/qt6 qtwayland, nix flakes enabled.

modules/apps.nix

@@ -1,14 +1,21 @@
 { config, pkgs, ... }:
 
 let
+
   # Both SDR++ and rtl_433 default to supporting every radio ever made, which
-  # drags in UHD (USRP firmware), BladeRF and LimeSuite — ~1.5 GB for hardware
-  # we don't own. These two overrides cut that down to the RTL-SDR paths.
+  # drags in UHD (USRP firmware), BladeRF and LimeSuite — ~1.5 GB for
+  # hardware we don't own. These two overrides cut that down to the RTL-SDR paths.
+
   soapysdrLean = pkgs.soapysdr.override {
-    extraPackages = with pkgs; [ soapyrtlsdr soapyremote ];
+    extraPackages = with pkgs; [
+      soapyrtlsdr
+      soapyremote
+    ];
   };
 
-  rtl433Lean = pkgs.rtl_433.override { soapysdr-with-plugins = soapysdrLean; };
+  rtl433Lean = pkgs.rtl_433.override {
+    soapysdr-with-plugins = soapysdrLean;
+  };
 
   # Leaves the RTL-SDR, rtl_tcp, file and network sources on.
   sdrppLean = pkgs.sdrpp.override {
@@ -23,15 +30,17 @@ let
     dragonlabs_source = false;
     spectran_http_source = false;
   };
+
 in
 {
   users.users."nexoniarz".packages = with pkgs; [
+
     tumbler
     brightnessctl
     ddcutil
-    lm_sensors                # sensors-detect helps ddcutil find the I2C buses
+    lm_sensors
     networkmanager
-    xdg-user-dirs             # Resolves localized folder names (Obrazy, not Pictures)
+    xdg-user-dirs
 
     # Apps
     blender
@@ -46,6 +55,8 @@ in
     obs-studio
     sdrppLean
     rtl433Lean
+    lmms
+    openrgb
 
     # Games
     prismlauncher
@@ -86,5 +97,8 @@ in
     kdePackages.konsole
     kdePackages.dolphin
     kdePackages.plasma-systemmonitor
+    qt5.qtwayland
+    qt6.qtwayland
+    qemu
   ];
 }

modules/desktop.nix

@@ -1,13 +1,14 @@
 { config, pkgs, ... }:
 
 {
-  # Budgie ships only a Wayland session here (labwc); xserver stays on for
-  # Xwayland and for the xkb layout below.
+  # Plasma ships a proper Wayland session (KWin) with solid Xwayland
+  # support; xserver stays on for that Xwayland layer and for the xkb
+  # layout below, not because the session itself needs it.
   services.xserver.enable = true;
-  services.desktopManager.budgie.enable = true;
+  services.desktopManager.plasma6.enable = true;
 
-  # SDDM replaces lightdm: Qt, and it actually launches Wayland sessions.
-  # Its own greeter runs on weston, not kwin, so no KDE compositor tags along.
+  # SDDM is KDE's own greeter — Qt-based, and launches Wayland sessions
+  # natively, Plasma included.
   services.displayManager.sddm = {
     enable = true;
     wayland.enable = true;
@@ -26,28 +27,11 @@
   # xserver.nix installs xterm unconditionally; Konsole is the terminal here.
   services.xserver.excludePackages = [ pkgs.xterm ];
 
-  # Budgie's module installs GTK/MATE apps that duplicate the Qt ones in
-  # apps.nix. Excluding gnome-terminal also flips programs.gnome-terminal.enable
-  # off — the module gates that on this same list.
-  environment.budgie.excludePackages = with pkgs; [
-    nemo                 # -> dolphin
-    gnome-terminal       # -> konsole
-    eom                  # -> gwenview
-    pluma                # -> kate
-    atril                # -> okular
-    engrampa             # -> ark
-    mate-calc            # -> kcalc
-    mate-system-monitor  # -> plasma-systemmonitor
-  ];
-
+  # Icon/cursor theme packages. Plasma has no gsettings-style declarative
+  # knob for this the way Budgie did — pick them in System Settings, or
+  # bring in plasma-manager later for a fully declarative setup.
   environment.systemPackages = [
     pkgs.gruvbox-plus-icons
     pkgs.bibata-cursors
   ];
-
-  services.desktopManager.budgie.extraGSettingsOverrides = ''
-    [org.gnome.desktop.interface]
-    icon-theme='Gruvbox-Plus-Dark'
-    cursor-theme='Bibata-Modern-Classic'
-  '';
 }

modules/system.nix

@@ -27,7 +27,6 @@
   };
   boot.kernelPackages = pkgs.linuxPackages;
   boot.supportedFilesystems = [ "fuse" ];
-
   networking.hostName = "nixos";
   networking.networkmanager.enable = true;
 
@@ -59,7 +58,7 @@
     dates = "weekly";
     options = "--delete-older-than 7d";
   };
-
+  
   console.keyMap = "pl2";
 
   security.rtkit.enable = true;
@@ -85,6 +84,11 @@
     };
   };
 
+  services.udev.extraRules = ''
+    # OpenRGB
+    SUBSYSTEM=="i2c-dev", GROUP="i2c", MODE="0660"
+  '';
+
   services.blueman.enable = true;
 
   programs.firejail = {
@@ -133,6 +137,8 @@
   ];
   environment.systemPackages = [ pkgs.file ];
 
+  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+
   # --- Hardening ---
 
   # zram instead of disk swap: nothing sensitive is written to disk in
@@ -140,7 +146,7 @@
   # old swap partition regardless of swapDevices, hence the kernel param.
   zramSwap.enable = true;
   swapDevices = lib.mkForce [ ];
-  boot.kernelParams = [ "systemd.gpt_auto=0" ];
+  boot.kernelParams = [ "systemd.gpt_auto=0" "acpi_enforce_resources=lax" ];
 
   boot.kernel.sysctl = {
     "kernel.kptr_restrict" = 2;
@@ -160,6 +166,10 @@
 
   systemd.coredump.enable = false;
   security.protectKernelImage = true;
+   
+  systemd.tmpfiles.rules = [
+    "L+ /var/lib/flatpak/exports/share/applications - - - - /var/lib/flatpak/app/com.usebottles.bottles/current/active/export/share/applications"
+  ];
 
   networking.nameservers = [ "1.1.1.1#cloudflare-dns.com" "9.9.9.9#dns.quad9.net" ];
   services.resolved = {
@@ -182,6 +192,9 @@
     uri = "";
     interval = 0;
   };
-
+  services.hardware.openrgb = {
+    enable = true;
+    motherboard = "amd";
+  };
   services.geoclue2.enable = false;
 }