Switch desktop environment from Hyprland to Pantheon

Configures Pantheon (LightDM + gala) for daily use on this ASUS TUF
Gaming A15 (FA507NU), and drops everything that only existed to serve
the previous Hyprland/Quickshell setup:

- desktop.nix: services.desktopManager.pantheon instead of
  programs.hyprland + greetd; comfy laptop touchpad defaults.
- drivers.nix: NVIDIA PRIME render offload between the AMD Radeon 680M
  (drives the panel) and the RTX 4050 Max-Q (offload-only), using this
  machine's real PCI bus IDs; asusd/supergfxd for ASUS-specific laptop
  control.
- apps.nix / scripts.nix: removed Hyprland/Quickshell-only packages and
  scripts (kitty, rofi, quickshell, mako, hyprlock, hyprpaper/mpvpaper,
  the Quickshell theme-picker scripts, cursor/wallpaper/display
  helpers) — Pantheon ships its own Files/Terminal/Screenshot/
  notifications/theming natively. Kept the DE-agnostic scripts (vault
  toggle, metadata stripping, brightness control, Wi-Fi hotspot,
  telemetry, weather).
- theme.nix and default-apps.nix deleted entirely — Pantheon owns
  GTK/icon theming itself, no more live dconf/CSS generation pipeline
  needed.
- Deleted hyprland/ and dotfiles/ (kitty, mako, quickshell, rofi).

Verified with `nixos-rebuild build`.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RpiovBQL6k5MTDMN3Ln9nL

modules/drivers.nix

@@ -0,0 +1,79 @@
+{ config, lib, pkgs, ... }:
+
+{
+  # Enable graphics driver support and 32-bit acceleration (for Steam/gaming)
+  hardware.graphics = {
+    enable = true;
+    enable32Bit = true;
+  };
+
+  #OpenTabletDriver
+  hardware.opentabletdriver.enable = true;
+  hardware.uinput.enable = true;
+  boot.kernelModules = [ "uinput" "v4l2loopback" ];
+
+  # Virtual webcam device so ffmpeg (fed by the GoPro's stream) can appear
+  # as a normal camera to apps like Discord. exclusive_caps=1 is required
+  # for Chromium/WebRTC-based apps to recognize it as a real capture device.
+  boot.extraModulePackages = [ config.boot.kernelPackages.v4l2loopback ];
+  boot.extraModprobeConfig = ''
+    options v4l2loopback devices=1 video_nr=10 card_label="GoPro Webcam" exclusive_caps=1
+    # PS4/PS5 controllers (e.g. DualSense) connect over Bluetooth then
+    # immediately disconnect — a well-known Linux Bluetooth stack issue
+    # where many adapters' Enhanced Retransmission Mode implementation is
+    # broken. Disabling ERTM is the standard, widely-documented fix.
+    options bluetooth disable_ertm=1
+  '';
+
+  # I2C bus, for DDC/CI monitor control (brightness) via ddcutil, when
+  # driving an external monitor over DisplayPort/HDMI. The internal panel
+  # uses the kernel backlight class instead (brightness-ctl picks whichever
+  # applies — see modules/scripts/brightness-ctl.sh).
+  hardware.i2c.enable = true;
+
+  # --- Hybrid graphics: AMD Radeon 680M (iGPU, drives the internal panel)
+  # + NVIDIA RTX 4050 Max-Q (dGPU, offload-only) — ASUS TUF Gaming A15
+  # FA507NU. Bus IDs come straight from `lspci` on this machine, not
+  # guessed: 01:00.0 (NVIDIA) -> PCI:1:0:0, 35:00.0 (AMD) -> PCI:53:0:0.
+  services.xserver.videoDrivers = [ "nvidia" ];
+
+  hardware.nvidia = {
+    # Required settings
+    modesetting.enable = true;
+
+    # Enable NVIDIA Open GPU Kernel Modules (Turing architecture or newer —
+    # this RTX 4050 is Ada Lovelace, well within support)
+    open = true;
+
+    # Enable the NVIDIA settings menu
+    nvidiaSettings = true;
+
+    # Use the stable driver package matching current kernel
+    package = config.boot.kernelPackages.nvidiaPackages.stable;
+
+    # Fixes suspend/resume hangs that are common with NVIDIA on laptops.
+    powerManagement.enable = true;
+
+    # PRIME render offload: the AMD iGPU drives the display at all times
+    # (much better battery life than keeping the dGPU powered on), and the
+    # NVIDIA GPU is only spun up on demand for a specific process — run
+    # anything with `nvidia-offload <command>` (generated by
+    # enableOffloadCmd) to route it through the RTX 4050, e.g. games or
+    # Blender's Cycles renderer.
+    prime = {
+      offload = {
+        enable = true;
+        enableOffloadCmd = true;
+      };
+      amdgpuBusId = "PCI:53:0:0";
+      nvidiaBusId = "PCI:1:0:0";
+    };
+  };
+
+  # ASUS laptop control: keyboard backlight/fan curves/battery charge limit
+  # (asusctl) and dGPU power-state switching between Integrated/Hybrid modes
+  # (supergfxctl) — the two standard asus-linux.org daemons for ROG/TUF
+  # laptops, both packaged directly in nixpkgs.
+  services.asusd.enable = true;
+  services.supergfxd.enable = true;
+}