Add animated glass background, breadcrumbs, and brand mark polish

Cards now sit on an animated signature-gradient background and use a
translucent, blurred bp-glass surface so it shines through; extended
bp-glass to every stat surface on the Stats page and to its tab switcher.
Adds a Breadcrumbs component below the header on all app pages.

Also: drop the gradient text fill from the wordmark/heading, animate the
BrandMark's heart and curve on the dashboard hero instead of a plain pulse
ring, recenter the heart/curve artwork in icon.svg and BrandMark, close the
mobile nav menu on link click, remove the redundant "back to recordings"
button, and match the "Start session"/"Scan for devices" button sizes.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/(app)/layout.tsx

@@ -1,10 +1,14 @@
 import { NavBar } from "@/components/layout/NavBar";
+import { Breadcrumbs } from "@/components/layout/Breadcrumbs";
 
 export default function AppLayout({ children }: { children: React.ReactNode }) {
   return (
     <div className="min-h-dvh">
       <NavBar />
-      <main className="mx-auto max-w-6xl px-4 py-8">{children}</main>
+      <main className="mx-auto max-w-6xl px-4 py-8">
+        <Breadcrumbs />
+        {children}
+      </main>
     </div>
   );
 }