create-host: fix flake.nix indentation patterns

The regex patterns expected 6 spaces of indentation but flake.nix uses
8 spaces for host entries. Also updated generated entry template to
match current flake.nix style (using commonModules ++).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/create-host/manipulators.py

@@ -152,15 +152,8 @@ def update_flake_nix(config: HostConfig, repo_root: Path, force: bool = False) -
           specialArgs = {{
             inherit inputs self sops-nix;
           }};
-        modules = [
-          (
-            {{ config, pkgs, ... }}:
-            {{
-              nixpkgs.overlays = commonOverlays;
-            }}
-          )
+          modules = commonModules ++ [
             ./hosts/{config.hostname}
-          sops-nix.nixosModules.sops
           ];
         }};
 """