Update OC logos to refined lockup; rebuild favicon from the open-o mark

Swap nav/footer logos for the updated black/white lockups (Asset 34/36); add
outline variants + the standalone open-o mark to the brand set. Rebuild the
favicon on the distinctive off-center open-o (paper on navy) instead of the
generic centered ring.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/brand/oc-open-o.svg

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg id="Layer_2" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 538.12 538.12">
+  <defs>
+    <style>
+      .cls-1 {
+        fill: #fff;
+      }
+    </style>
+  </defs>
+  <g id="Layer_1-2" data-name="Layer_1">
+    <path class="cls-1" d="M269.06,0C120.46,0,0,120.46,0,269.06s120.46,269.06,269.06,269.06,269.06-120.46,269.06-269.06S417.66,0,269.06,0ZM276.06,356.34c-48.2,0-87.28-39.07-87.28-87.28s39.07-87.28,87.28-87.28,87.28,39.08,87.28,87.28-39.07,87.28-87.28,87.28Z"/>
+  </g>
+</svg>