refactor: Move nix outside of .config dir

Technically not a config but a compose file, so I think it's better to
have outside of `.config` dir

nix/users/ziro/default.nix

@@ -0,0 +1,48 @@
+{ pkgs, pkgs-unstable, config, vars, ... }:
+
+let
+  username = "ziro";
+  userChrome = builtins.replaceStrings ["/*ZI:VERTICAL-TAB-HOVER-WIDTH-IN-EM*/"] ["${builtins.toString vars.floorp.verticalTabHoverWidthInEm}em"] (builtins.readFile ../../files/floorp/ziro-userChrome.css);
+  settings = {
+    "browser.toolbars.bookmarks.visibility" = "newtab";
+    "floorp.browser.sidebar.is.displayed" = false;
+    "floorp.browser.tabbar.settings" = 2;
+    "floorp.browser.tabs.verticaltab" = true;
+    "floorp.verticaltab.hover.enabled" = true;
+    "floorp.tabbar.style" = 2;
+    "network.dns.disableIPv6" = true;
+    "sidebar.position_start" = false;
+    "signon.management.page.breach-alerts.enabled" = false;
+    "signon.rememberSignons" = false;
+    "extensions.autoDisableScopes" = 0;  # Auto enable extensions
+  };
+  extensions = with pkgs.nur.repos.rycee.firefox-addons; [
+    passff
+    ublock-origin
+  ];
+in {
+  home = {
+    inherit username;
+    packages =
+      [
+        pkgs.passff-host
+      ];
+  };
+
+  programs.floorp.profiles.${username} = {
+    inherit userChrome settings extensions;
+  };
+  programs.floorp.profiles.null = {
+    id = 1;
+    inherit userChrome settings extensions;
+  };
+
+  xdg.configFile = {
+    "nix/nix.conf".text =
+      ''
+        experimental-features = nix-command flakes
+      '';
+  };
+
+  home.stateVersion = "24.11";
+}