fix: logo and custom branding (#10930)

This PR has the following changes

1. Update `Logo.vue` to fetch the logo from globalConfig and fallback to
SVG if required.
2. Update the default `public/brand-assets/logo_thumbnail.svg` to use
the new colors.

### Preview


https://github.com/user-attachments/assets/505a1d05-cd05-4b86-9fe7-c05334f09b25

![CleanShot 2025-02-19 at 10 56
23@2x](https://github.com/user-attachments/assets/084064b9-5df5-4d11-9b6a-b511c6047001)

app/javascript/dashboard/components-next/sidebar/Sidebar.vue

@@ -525,7 +525,7 @@ const menuItems = computed(() => {
     <section class="grid gap-2 mt-2 mb-4">
       <div class="flex items-center min-w-0 gap-2 px-2">
         <div class="grid flex-shrink-0 size-6 place-content-center">
-          <Logo />
+          <Logo class="size-4" />
         </div>
         <div class="flex-shrink-0 w-px h-3 bg-n-strong" />
         <SidebarAccountSwitcher