Add linting, formatting, and CI with fixes for all warnings

Infrastructure:
- Add deadnix, nixfmt, and statix to flake inputs
- Add formatter output to flake for nix fmt support
- Add deadnix, nixfmt, statix to Home Manager packages
- Add GitHub Actions workflow for CI validation
- Add .pre-commit-config.yaml with hooks for nixfmt, deadnix, and statix
- Support x86_64-darwin in formatter

Statix fixes (W10/W20 warnings):
- Remove unused lambda argument from nixpkgs-settings.nix
- Merge repeated keys in hardware-configuration.nix files (boot.initrd, boot, fileSystems)
- Merge repeated keys in nixnuc/default.nix (services, virtualisation)
- Merge repeated keys in rainbow-planet/default.nix (desktopManager)
- Merge repeated keys in home/general/default.nix (home)

Deadnix fixes (unused declarations):
- Remove unused pkgs/lib/username/http_port arguments from various files
- Fix unused final parameter in overlay functions (final -> _final)

CI/pre-commit fixes:
- Fix pre-commit statix config: add pass_filenames: false
- Fix CI workflow: use nix run nixpkgs# prefix and --ci flag for nixfmt

modules/hosts/nixos/bigboy/default.nix

@@ -1,14 +1,20 @@
-{ config, pkgs, username, ... }:
-  let
-    libbluray = pkgs.libbluray.override {
-      withAACS = true;
-      withBDplus = true;
-      withJava = true;
-    };
-    vlc-with-decoding = pkgs.vlc.override { inherit libbluray; };
-  in
 {
-  imports = [ # Include the results of the hardware scan.
+  config,
+  pkgs,
+  username,
+  ...
+}:
+let
+  libbluray = pkgs.libbluray.override {
+    withAACS = true;
+    withBDplus = true;
+    withJava = true;
+  };
+  vlc-with-decoding = pkgs.vlc.override { inherit libbluray; };
+in
+{
+  imports = [
+    # Include the results of the hardware scan.
     ./hardware-configuration.nix
     ../../../shared/nixos/flatpaks.nix
     ../../../shared/nixos/ripping.nix
@@ -43,7 +49,6 @@
     zoom-us
   ];
 
-  
   networking.networkmanager.enable = true;
 
   programs = {
@@ -118,10 +123,15 @@
   users.users.${username} = {
     isNormalUser = true;
     description = "Gene Liverman";
-    extraGroups = [ "networkmanager" "wheel" "dialout" "input" ];
+    extraGroups = [
+      "networkmanager"
+      "wheel"
+      "dialout"
+      "input"
+    ];
     packages = with pkgs; [
       kdePackages.kate
-    #  thunderbird
+      #  thunderbird
     ];
   };
 }