meta: use treefmt (#3)

Reviewed-on: https://codeberg.org/comfysage/ebil/pulls/3
Co-authored-by: june <[e-mail]>
Co-committed-by: june <[e-mail]>

.envrc

···
 if has nix; then
-  use flake
+	use flake
 fi

ebil.sh

···
 	name="${site%.ebil.club}"
 
 	msg 'user:' "$name"
-  [[ -f "${path}/index.txt" ]] && msg 'custom curl message configured' "(${path}/index.txt)"
+	[[ -f "${path}/index.txt" ]] && msg 'custom curl message configured' "(${path}/index.txt)"
 
 	msg 'pushing to' "$site" 'from' "$path"
 	rsync -rltzq --progress --delete --chmod=D755,F644 "${path}/" "${host}:/var/ebil.club/${name}/${site}"

flake.nix

···
       });
 
       overlays.default = final: _: { ebil = final.callPackage ./nix/package.nix { }; };
+
+      formatter = forAllSystems (pkgs: pkgs.callPackage ./nix/formatter.nix { });
     };
 }

nix/formatter.nix

···
+{
+  treefmt,
+  nixfmt,
+  shfmt,
+}:
+treefmt.withConfig {
+  runtimeInputs = [
+    nixfmt
+    shfmt
+  ];
+  settings = {
+    on-unmatched = "warn";
+    tree-root-file = "flake.nix";
+    formatter = {
+      nix = {
+        command = "nixfmt";
+        includes = [ "*.nix" ];
+      };
+      shfmt = {
+        command = "shfmt";
+        options = [ "-w" ];
+        includes = [
+          "*.sh"
+          ".envrc"
+        ];
+      };
+    };
+  };
+}

nix/shell.nix

···
-{ mkShellNoCC, shellcheck, shfmt }:
+{
+  mkShellNoCC,
+  shellcheck,
+  shfmt,
+}:
 mkShellNoCC {
   packages = [
     shellcheck