fix(static): center avatar favicon and use pure black/white for light/dark modes

static/astrion-avatar.svg

@@ -1,7 +1,7 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 200 200" aria-hidden="true">
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 -4 200 200" aria-hidden="true">
   <style>
     .sa-frame, .sa-eye {
-      stroke: #181818;
+      stroke: #000000;
       stroke-linecap: round;
       stroke-linejoin: round;
       fill: none;
@@ -14,7 +14,7 @@
     }
     @media (prefers-color-scheme: dark) {
       .sa-frame, .sa-eye {
-        stroke: #faf9f5;
+        stroke: #ffffff;
       }
     }
   </style>