feat: optimize img load time by Jekyll hosted file

Problem: Now it doesn't work on local machines...

docs/beta.html

@@ -10,7 +10,7 @@
     />
     <style>
       :root {
-        --background-url: url("https://github.com/JANERUBBISHTOEAT/Shawarma-Legend-Save/blob/main/docs/images/home_empty.png?raw=true");
+        --background-url: url("/Shawarma-Legend-Save/images/home_empty.png");
       }
       body {
         font-family: Arial, sans-serif;