refactor: separate module options into options.nix

modules/forgejo/options.nix

@@ -0,0 +1,45 @@
+args@{ config, lib, ... }:
+{
+  options.aether = {
+    inherit (import ../options.nix args)
+      domain
+      https
+      acmeEmail;
+
+    forgejo = {
+      subdomain = lib.mkOption {
+        type = lib.types.nullOr lib.types.str;
+        default = "git";
+        description = ''
+          The subdomain to host the Forgejo instance under.
+
+          If null, then Forgejo is hosted at the domain itself.
+        '';
+      };
+
+      user = lib.mkOption {
+        type = lib.types.str;
+        default = "git";
+        description = ''
+          The user to run Forgejo with.
+        '';
+      };
+
+      createUser = lib.mkOption {
+        type = lib.types.bool;
+        default = true;
+        description = ''
+          Whether to create the Forgejo user automatically.
+        '';
+      };
+
+      templates = lib.mkOption {
+        type = lib.types.nullOr lib.types.path;
+        default = null;
+        description = ''
+          A directory of templates for customizing Forgejo's appearance.
+        '';
+      };
+    };
+  };
+}