Add new logo and SVG icons for improved UI

- Added a new PNG logo image to enhance branding.
- Introduced a new SVG icon for matrix representation with dark mode support.
- Included a PNG image for "no search found" scenario to improve user experience.

themes/chill-theme/layouts/_default/baseof.html

@@ -92,7 +92,7 @@
     {{ partial "footer" . }}
 
     <!-- Language Preference Script -->
-    {{ if .Site.IsMultiLingual }}
+    {{ if hugo.IsMultilingual }}
     {{ if .Site.Params.visitorapi_pid }}
     <script>
         // Inject VisitorAPI project ID from Hugo config