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/services/zfs/auto-mount-volumes.nix

@@ -1,12 +1,12 @@
 { pkgs, boot, ... }:
 
 {
-boot.postBootCommands = ''
-  echo "=== STARTING ZPOOL IMPORT ==="
-  ${pkgs.zfs_unstable}/bin/zpool import -a -N -d /dev/disk/by-path
-  ${pkgs.zfs_unstable}/bin/zpool status
-  ${pkgs.zfs_unstable}/bin/zfs mount -a
-  ${pkgs.zfs_unstable}/bin/zfs list
-    echo "=== ZPOOL IMPORT COMPLETE ==="
-'';
- }
+  boot.postBootCommands = ''
+    echo "=== STARTING ZPOOL IMPORT ==="
+    ${pkgs.zfs_unstable}/bin/zpool import -a -N -d /dev/disk/by-path
+    ${pkgs.zfs_unstable}/bin/zpool status
+    ${pkgs.zfs_unstable}/bin/zfs mount -a
+    ${pkgs.zfs_unstable}/bin/zfs list
+      echo "=== ZPOOL IMPORT COMPLETE ==="
+  '';
+}

modules/services/zfs/enable-service.nix

@@ -1,16 +1,21 @@
 { pkgs, ... }:
 
- {
-boot.supportedFilesystems = [ "zfs" ];
-  boot.zfs.forceImportRoot = false;
-  boot.zfs.package = pkgs.zfs_unstable;
-      services.zfs = {
+{
+  boot = {
+    supportedFilesystems = [ "zfs" ];
+    zfs = {
+      forceImportRoot = false;
+      package = pkgs.zfs_unstable;
+      devNodes = "/dev/disk/by-id";
+    };
+  };
+
+  services.zfs = {
     autoScrub.enable = true;
     autoSnapshot.enable = true;
     trim.enable = true;
   };
 
-#systemd.services.zfs-import-cache.enable = true;
-systemd.services.zfs-mount.enable = true;
-boot.zfs.devNodes = "/dev/disk/by-id";
- }
+  #systemd.services.zfs-import-cache.enable = true;
+  systemd.services.zfs-mount.enable = true;
+}