Bring laptop in line with desktop config: Plasma 6, Limine, module split

The laptop was still on the Hyprland-era Pantheon commit while the desktop
moved to KDE Plasma 6 + Limine and split system.nix into focused modules.
This brings over everything that isn't hardware, unchanged, so both machines
stay diffable:

- Plasma 6 on Wayland with SDDM, Konsole, gruvbox icons, KDE MIME defaults
  (replaces Pantheon/LightDM; libreoffice-qt6 replaces the GTK build)
- Limine bootloader with the gruvbox theme, replacing systemd-boot
- system.nix split into boot/networking/locale/nix-settings/security
- flakes + nix-command, sysctl hardening extras (yama, tcp_timestamps),
  geoclue off, captive-portal probe off
- package parity: obs-studio, lmms, go, qemu, KDE utilities, lean SDR++ and
  rtl_433 overrides with hardware.rtl-sdr

Hardware and power are adapted rather than copied:

- hardware.nix keeps the AMD 680M + RTX 4050 PRIME offload setup, asusd and
  supergfxd, v4l2loopback webcam and the DualSense ERTM fix; OpenRGB and
  the desktop's single-GPU block are dropped, keyboard lighting is asusctl
- power.nix is new: power-profiles-daemon for Plasma's profile switcher,
  lid-close handling via the current logind.settings.Login spelling,
  powertop/acpi, notes on asusctl charge limits
- no acpi_enforce_resources=lax, ACPI owns the EC asusd drives here
- touchpad defaults, and firewall openings so the hotspot script's shared
  connection can hand out DHCP/DNS
- pinentry-qt instead of the desktop's leftover pinentry-rofi, blueman
  dropped in favour of Plasma's bluedevil

hardware-configuration.nix stays tracked here (unlike the desktop, which
gitignores it) since it's the only record of this machine's disk layout.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

modules/apps.nix

@@ -1,16 +1,46 @@
 { 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.
+
+  soapysdrLean = pkgs.soapysdr.override {
+    extraPackages = with pkgs; [
+      soapyrtlsdr
+      soapyremote
+    ];
+  };
+
+  rtl433Lean = pkgs.rtl_433.override {
+    soapysdr-with-plugins = soapysdrLean;
+  };
+
+  # Leaves the RTL-SDR, rtl_tcp, file and network sources on.
+  sdrppLean = pkgs.sdrpp.override {
+    soapy_source = false;
+    bladerf_source = false;
+    limesdr_source = false;
+    plutosdr_source = false;
+    airspy_source = false;
+    airspyhf_source = false;
+    hermes_source = false;
+    rfspace_source = false;
+    dragonlabs_source = false;
+    spectran_http_source = false;
+  };
+
+in
 {
-  # Every installed package — GUI apps, CLI tools, and dev toolchains alike.
-  # If it's "install X", it goes here.
   users.users."nexoniarz".packages = with pkgs; [
-    # Hardware control (Pantheon itself ships Files/Terminal/Screenshot/
-    # notifications/dock/launcher — see services.desktopManager.pantheon
-    # in modules/desktop.nix, nothing to list here for those)
-    brightnessctl              # Backlight brightness (internal laptop panel)
-    ddcutil                    # DDC/CI brightness (external monitors)
-    lm_sensors                 # sensors-detect helps ddcutil find I2C buses; also feeds asusctl
-    networkmanager             # nmcli, for the Wi-Fi hotspot script
+
+    tumbler
+    brightnessctl        # Backlight on the internal panel
+    ddcutil              # DDC/CI brightness on an external monitor
+    lm_sensors           # sensors-detect also helps ddcutil find its I2C buses
+    networkmanager       # nmcli, for the Wi-Fi hotspot script
+    xdg-user-dirs
 
     # Apps
     blender
@@ -22,35 +52,65 @@
     vlc
     filezilla
     chromium
+    obs-studio
+    sdrppLean
+    rtl433Lean
+    lmms
 
     # Games
     prismlauncher
-    pkgs.osu-lazer-bin
+    osu-lazer-bin
 
-    # Dev: compilers, runtimes, languages
+    # Dev
     glibc
     musl
     cmake
-    gnumake # Provides the 'make' command
+    gnumake
     gcc
     python3
     openjdk25
-    claude-code # AI Developer Assistant
+    go
+    claude-code
   ];
 
-  # Global command-line utilities available everywhere
   environment.systemPackages = with pkgs; [
     git
-    gh # GitHub CLI — was only installed ad-hoc before (login didn't survive)
+    gh
     vim
     fastfetch
     gparted
+    efibootmgr
     firejail
     gnupg
     lmstudio
+    kdePackages.ark
     p7zip
     unzip
     unrar
-    libreoffice # GTK3 build — matches Pantheon's native GTK theming, unlike the Qt build
+    kdePackages.gwenview
+    kdePackages.kate
+    kdePackages.qqc2-desktop-style
+    linphonePackages.linphone-desktop
+    kdePackages.kcalc
+    kdePackages.okular
+    kdePackages.elisa
+    kdePackages.konsole
+    kdePackages.dolphin
+    kdePackages.plasma-systemmonitor
+    qt5.qtwayland
+    qt6.qtwayland
+    qemu
+    file
+  ];
+
+  # Lets non-Nix binaries (e.g. the Tor Browser bundle) find an FHS linker.
+  programs.nix-ld.enable = true;
+  programs.nix-ld.libraries = with pkgs; [
+    glib gtk3 gdk-pixbuf pango cairo atk
+    dbus dbus-glib fontconfig freetype
+    libx11 libxext libxrender libxtst
+    libxi libxcomposite libxdamage libxfixes
+    libxrandr libxcursor libxcb libxkbcommon
+    alsa-lib mesa zlib stdenv.cc.cc
   ];
 }