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/common/home.nix

@@ -10,9 +10,25 @@ in
     ./aliases.nix
   ];
 
-  home.username = vars.primaryUser;
-  home.homeDirectory = "/home/${vars.primaryUser}";
-  home.stateVersion = "25.11"; # match your NixOS stateVersion
+  home = {
+    username = vars.primaryUser;
+    homeDirectory = "/home/${vars.primaryUser}";
+    stateVersion = "25.11"; # match your NixOS stateVersion
+
+    # Optional: packages
+    packages = with pkgs; [
+      git
+      vim
+      tmux
+      nano
+      sshfs
+    ];
+
+    # Optional: set environment vars
+    sessionVariables = {
+      EDITOR = "nano";
+    };
+  };
 
   programs.home-manager.enable = true; # mandatory to activate HM
 
@@ -23,19 +39,6 @@ in
   # modules/common/configuration.nix instead (covers the daemon for every
   # user, not just this one).
 
-  # Optional: packages
-  home.packages = with pkgs; [
-    git
-    vim
-    tmux
-    nano
-    sshfs
-  ];
-
-  # Optional: set environment vars
-  home.sessionVariables = {
-    EDITOR = "nano";
-  };
   #  systemd.user.services.mount-proxmox-iso = {
   #    Unit = {
   #      Description = "Mount Proxmox ISO dir via SSHFS";