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>

README.md

@@ -1,14 +1,18 @@
 # nexoniarz-config-nixos-laptop
 
 My personal NixOS system configuration tailored for daily use on an
-**ASUS TUF Gaming A15 (FA507NU)**.
+**ASUS TUF Gaming A15 (FA507NU)**. Same layout and same choices as
+[nexoniarz-config-nixos](https://github.com/Nexoniarz/nexoniarz-config-nixos)
+(the desktop), with the hardware and power modules swapped for this machine.
 
 ## Overview
 
-- **OS:** NixOS
-- **DE / Compositor:** Pantheon (gala, Wayland)
-- **Display manager:** LightDM (elementary greeter)
+- **OS:** NixOS 26.05 (unstable channel)
+- **Desktop:** KDE Plasma 6 on Wayland (KWin), SDDM
+- **Bootloader:** Limine
+- **Terminal:** Konsole
 - **Shell:** Zsh
+- **Audio:** PipeWire
 - **CPU:** AMD Ryzen 5 7535HS
 - **GPU:** AMD Radeon 680M (iGPU, drives the internal panel) + NVIDIA RTX
   4050 Max-Q (dGPU, PRIME render offload only — run anything through it with
@@ -18,19 +22,44 @@ My personal NixOS system configuration tailored for daily use on an
 
 ## Layout
 
-- `configuration.nix` — top-level imports
-- `hardware-configuration.nix` — generated by `nixos-generate-config`, don't
-  hand-edit
-- `modules/system.nix` — bootloader, networking, time, sound, hardening,
-  nix-ld
-- `modules/drivers.nix` — hybrid graphics (NVIDIA PRIME offload), ASUS
-  daemons, misc hardware (webcam loopback, tablet driver)
-- `modules/desktop.nix` — Pantheon desktop environment
-- `modules/users.nix` — user account, Steam, Firefox, Flatpak
-- `modules/apps.nix` — all installed packages
-- `modules/scripts.nix` + `modules/scripts/` — small custom CLI helpers
-  (encrypted vault toggle, metadata stripping, brightness control, Wi-Fi
-  hotspot, system telemetry, weather fetch)
+| File | Contents |
+|---|---|
+| `configuration.nix` | Imports only |
+| `hardware-configuration.nix` | Generated by `nixos-generate-config`, don't hand-edit |
+| `modules/boot.nix` | Limine, kernel, zram/swap |
+| `modules/networking.nix` | NetworkManager, firewall, DNS-over-TLS, MAC randomization |
+| `modules/locale.nix` | Timezone, locale, console keymap |
+| `modules/nix-settings.nix` | Nix features, GC, unfree |
+| `modules/security.nix` | sysctl hardening, sudo, firejail, GnuPG, polkit |
+| `modules/hardware.nix` | Hybrid graphics (PRIME offload), ASUS daemons, Bluetooth, I2C, RTL-SDR, webcam loopback, tablet, printing |
+| `modules/power.nix` | Power profiles, lid/suspend behaviour, battery notes |
+| `modules/audio.nix` | PipeWire |
+| `modules/desktop.nix` | Plasma, SDDM, touchpad, fonts, theming |
+| `modules/users.nix` | Account, shell, Steam, Flatpak |
+| `modules/apps.nix` | Installed packages, nix-ld |
+| `modules/default-apps.nix` | MIME associations |
+| `modules/scripts.nix` | Custom scripts in `modules/scripts/` |
+
+Small custom CLI helpers live in `modules/scripts/`: encrypted vault toggle,
+metadata stripping, brightness control (kernel backlight or DDC/CI), Wi-Fi
+hotspot, system telemetry, weather fetch.
+
+## Differences from the desktop config
+
+Everything outside hardware is kept identical on purpose. What differs:
+
+- `modules/hardware.nix` — AMD iGPU + NVIDIA dGPU on PRIME offload with
+  `asusd`/`supergfxd`, instead of the desktop's single NVIDIA card and
+  OpenRGB motherboard lighting. Keyboard lighting is `asusctl aura` here.
+- `modules/power.nix` — laptop-only module: power-profiles-daemon (Plasma's
+  power profile switcher), lid-close behaviour, `powertop`/`acpi`.
+- `modules/desktop.nix` — adds touchpad defaults and the Wayland/Ozone flag.
+- `modules/boot.nix` — no `acpi_enforce_resources=lax`; ACPI owns the EC that
+  `asusd` talks to on this machine.
+- `modules/networking.nix` — firewall openings for the hotspot script's
+  `ipv4.method shared` dnsmasq.
+- `modules/security.nix` — `pinentry-qt` (Plasma) rather than the desktop's
+  leftover `pinentry-rofi`.
 
 ---