Resolve all statix and nixpkgs-fmt warnings repo-wide

Zero W20 (repeated attribute keys), W10 (empty { ... }: variadic
pattern, use _: instead), and W04 (a = x.a instead of inherit)
warnings remain anywhere in the tree, and nixpkgs-fmt --check is
clean on all 46 .nix files.

Repeated-key merges go as deep as statix actually flags per file
(e.g. boot.loader.* nested under boot.loader = { ... } once the
outer boot.* merge exposed it as its own repeat) — every merge is a
pure attribute-path restructuring with no value changes, verified by
comparing config.system.build.toplevel.drvPath before/after for a
representative host per changed module plus a full 19-host + 4-package
eval sweep.

One indentation slip caught and fixed during this pass: nesting
modules/installer/common.nix's environment.etc."auto-install.sh".text
under an environment = { ... } block initially normalized the
script's shebang/set line indentation, which actually changes the
rendered file (Nix's '' string dedent treats it as real content, not
cosmetic whitespace) — reproduced the original's exact indentation
and reverified the rendered script is byte-identical to before.

modules/services/zfs/auto-mount-volumes.nix picked up formatting too;
worth noting it isn't imported by anything in this flake at all.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01La55Nsss8jZ7ZuzUV9mfot

modules/build-types/gui.nix

@@ -19,23 +19,47 @@
 
   boot.loader.grub.useOSProber = true;
 
-  services.xserver.enable = true;
-  services.xserver.displayManager.lightdm.enable = true;
-  services.xserver.desktopManager.cinnamon.enable = true;
+  services = {
+    xserver = {
+      enable = true;
 
-  services.xserver.xkb = {
-    layout = "au";
-    variant = "";
+      displayManager = {
+        lightdm.enable = true;
+        sessionCommands = ''
+          eval $(gnome-keyring-daemon --start --components=secrets,ssh)
+          export SSH_AUTH_SOCK
+        '';
+      };
+
+      desktopManager.cinnamon.enable = true;
+
+      xkb = {
+        layout = "au";
+        variant = "";
+      };
+    };
+
+    printing.enable = true;
+
+    pipewire = {
+      enable = true;
+      alsa.enable = true;
+      alsa.support32Bit = true;
+      pulse.enable = true;
+    };
+
+    xrdp = {
+      enable = true;
+      defaultWindowManager = "cinnamon-session";
+      openFirewall = true;
+    };
+
+    gnome.gnome-keyring.enable = true;
   };
 
-  services.printing.enable = true;
-
-  security.rtkit.enable = true;
-  services.pipewire = {
-    enable = true;
-    alsa.enable = true;
-    alsa.support32Bit = true;
-    pulse.enable = true;
+  security = {
+    rtkit.enable = true;
+    pam.services.login.enableGnomeKeyring = true;
   };
 
   # The networkmanager group only exists when NM is actually enabled — the
@@ -45,16 +69,5 @@
 
   programs.firefox.enable = true;
 
-  services.xrdp.enable = true;
-  services.xrdp.defaultWindowManager = "cinnamon-session";
-  services.xrdp.openFirewall = true;
   nixpkgs.config.allowUnfree = true;
-
-  services.gnome.gnome-keyring.enable = true;
-  security.pam.services.login.enableGnomeKeyring = true;
-
-  services.xserver.displayManager.sessionCommands = ''
-    eval $(gnome-keyring-daemon --start --components=secrets,ssh)
-    export SSH_AUTH_SOCK
-  '';
 }