feat(brand): adopt the redesigned InvoiceShelf logo (#660)

- MainLogo.vue: new 'receipt + check' mark + InvoiceShelf wordmark lockup
  (monochrome, inherits the existing light/dark colour props — works in the
  header, auth, installation, sidebar, loader, and customer portal).
- Favicons + PWA icons regenerated from the new mark (16/32/180/192/512/150 +
  favicon.ico); safari-pinned-tab.svg redrawn to the new mark; mask-icon colour
  #5851d8 -> #4a3dff.
- New brand SVG assets (logo-mark + variants + lockup) added under static/img;
  logo-gray.png (public-invoice footer) regenerated as the mono mark.

resources/views/app.blade.php

@@ -9,7 +9,7 @@
     <link rel="icon" type="image/png" sizes="32x32" href="/favicons/favicon-32x32.png">
     <link rel="icon" type="image/png" sizes="16x16" href="/favicons/favicon-16x16.png">
     <link rel="manifest" href="/favicons/site.webmanifest">
-    <link rel="mask-icon" href="/favicons/safari-pinned-tab.svg" color="#5851d8">
+    <link rel="mask-icon" href="/favicons/safari-pinned-tab.svg" color="#4a3dff">
     <link rel="shortcut icon" href="/favicons/favicon.ico">
     <meta name="msapplication-TileColor" content="#ffffff">
     <meta name="msapplication-config" content="/favicons/browserconfig.xml">