[Steam] added template + entry in the settings menu

Assets/Templates/steam.css

@@ -0,0 +1,7 @@
+:root {
+    --theme-color: "Matugen";
+    --hue-rotate: 220deg;
+    <* for name, value in colors *>
+    --md-sys-color-{{name | replace: "_", "-" }}: {{value.default.rgb}};
+    <* endfor *>
+}

Services/Theming/TemplateRegistry.qml

@@ -408,6 +408,17 @@ Singleton {
         }
       ],
       "postProcess": () => `${templateApplyScript} zathura`
+    },
+    {
+      "id": "steam",
+      "name": "Steam",
+      "category": "misc",
+      "input": "steam.css",
+      "outputs": [
+        {
+          "path": "~/.steam/steam/steamui/skins/Material-Theme/css/main/colors/matugen.css"
+        }
+      ],
     }
   ]