feat(web): favicon + toast feedback (polish)

Add a vinyl-record favicon (icon.svg) — fixes the favicon.ico 404 console
error. Lightweight toast system (ToastHost + toast()) fired on request, wanted
add, search, follow, and want actions so submits give explicit feedback.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/discover/discover-client.tsx

@@ -6,6 +6,7 @@ import { SectionHeader } from "../_ui/section-header";
 import { ArtistModal } from "../_ui/artist-modal";
 import { AlbumModal } from "../_ui/album-modal";
 import { CoverArt } from "../_ui/cover-art";
+import { toast } from "../_ui/toast";
 
 type Suggestion = {
   id: string;
@@ -86,6 +87,7 @@ export function DiscoverClient() {
     });
     if (res.ok || res.status === 409) {
       setFollowedSimilar((s) => new Set(s).add(a.mbid));
+      toast(`Following ${a.name}`);
     }
   }
 
@@ -95,6 +97,7 @@ export function DiscoverClient() {
       headers: { "content-type": "application/json" },
       body: JSON.stringify({ action }),
     });
+    toast(action === "follow" ? "Following" : action === "want" ? "Added to wanted" : "Dismissed");
     loadFeed();
   }