polish(web): favicon, Punktfunk casing, display-save toast, idle stop button

- Favicon: the brand-mark lens SVG at /favicon.svg, linked from the root head.
- Branding: user-facing "punktfunk" → "Punktfunk" (tab title, app_name,
  pairing prose, the logo aria-labels/SVG titles) — protocol identifiers
  (punktfunk/1, _punktfunk._udp, binary/module names) stay lowercase.
- The display policy auto-saves on every preset pick / field edit with no
  signal; mount @unom/ui's sonner Toaster in the root and fire a success toast
  from the save funnel's onSuccess (new i18n key, en + de). First toast usage
  in the console — errors stay inline as before.
- The stop-session button rendered destructive-red even with nothing to stop:
  variant switches to the muted `secondary` while no session is active.

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

web/src/components/app-shell.tsx

@@ -48,7 +48,7 @@ export function AppShell({ children }: { children: ReactNode }) {
 			<aside className="sticky top-0 hidden h-dvh w-60 shrink-0 flex-col overflow-y-auto border-r bg-card/40 p-4 sm:flex">
 				<Link
 					to="/"
-					aria-label="punktfunk"
+					aria-label="Punktfunk"
 					className="mb-7 flex items-center gap-2 px-2 pt-1"
 				>
 					<BrandMark className="size-7 drop-shadow-[0_2px_12px_rgba(108,91,243,0.45)]" />

web/src/components/brand-mark.tsx

@@ -5,13 +5,13 @@
 export function BrandMark({ className }: { className?: string }) {
 	return (
 		<svg
-			aria-label="punktfunk"
+			aria-label="Punktfunk"
 			role="img"
 			xmlns="http://www.w3.org/2000/svg"
 			viewBox="0 0 1000 1000"
 			className={className}
 		>
-			<title>punktfunk</title>
+			<title>Punktfunk</title>
 			<path
 				d="M403.037,791.672c107.586,0 194.41,-86.824 194.41,-194.41c0,-107.586 -86.824,-194.41 -194.41,-194.41c-107.586,0 -194.41,86.824 -194.41,194.41c0,107.586 86.824,194.41 194.41,194.41Z"
 				fill="#a79ff8"

web/src/components/wordmark.tsx

@@ -8,13 +8,13 @@ export function Wordmark({ className }: { className?: string }) {
 	return (
 		<svg
 			role="img"
-			aria-label="punktfunk"
+			aria-label="Punktfunk"
 			xmlns="http://www.w3.org/2000/svg"
 			viewBox="0 0 579 136"
 			fill="currentColor"
 			className={cn("w-auto text-highlight", className)}
 		>
-			<title>punktfunk</title>
+			<title>Punktfunk</title>
 			<path d="M16.782,16.051l0,102.687l31.253,0l0,-35.563l73.436,0l0,-23.555l-73.436,0l0,-19.398l77.285,0l0,-24.171l-108.537,0Z" />
 			<path d="M131.785,16.051l0,47.264c0.154,16.627 0.154,16.627 0.308,20.014c0.77,15.087 2.463,21.4 7.544,26.634c7.698,8.16 20.014,10.315 59.272,10.315c23.863,0 34.178,-0.616 43.415,-2.463c11.7,-2.463 19.552,-10.623 21.246,-22.323c0.924,-7.236 1.078,-8.929 1.54,-32.176l0,-47.264l-31.253,0l0,47.264c0,2.155 -0.154,7.082 -0.308,10.623c-0.462,9.699 -1.232,12.47 -3.695,15.087c-3.387,3.695 -9.853,4.619 -31.407,4.619c-26.634,0 -32.638,-1.693 -34.332,-9.853c-0.77,-4.157 -0.77,-4.311 -1.078,-20.476l0,-47.264l-31.253,0Z" />
 			<path d="M271.575,15.943l0,102.687l31.868,0l-0.77,-76.669l3.387,0l54.038,76.669l54.346,0l0,-102.687l-31.868,0l0.77,76.515l-3.233,0l-53.73,-76.515l-54.808,0Z" />