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/login/page.tsx

@@ -13,7 +13,7 @@ export default function LoginPage() {
         <CardHeader>
           <div className="flex items-center gap-2">
             <BrandMark size={32} />
-            <CardTitle className="font-heading bp-gradient-text text-2xl">Sexy</CardTitle>
+            <CardTitle className="font-heading text-2xl">Sexy</CardTitle>
           </div>
           <CardDescription>Enter the shared access secret to continue.</CardDescription>
         </CardHeader>