feat: share collection URL

components/social/collection/collection-scroll-card.tsx

@@ -21,15 +21,18 @@ import { useEffect, useRef, useState } from "react";
 import Image from "next/image";
 import Link from "next/link";
 import {
+  Check,
   ChevronLeft,
   ChevronRight,
   Globe,
+  Link2,
   Loader2,
   Lock,
   Pencil,
 } from "lucide-react";
 import { cn } from "@/lib/utils";
 import { collections, type Collection, type Post } from "@/lib/social";
+import { useCopyFeedback } from "@/components/selection-toolbar/shared";
 import { PostGridCard } from "../post/post-grid-card";
 import { quoteCardBgStyle } from "../post/post-card-shared";
 
@@ -201,6 +204,7 @@ function CoverSlide({
   href: string;
   onEdit?: () => void;
 }) {
+  const { copied, copy } = useCopyFeedback();
   // The slide wrapper hosts the Link AND any owner-action chip as
   // siblings. Nesting a button inside the Link is an a11y anti-pattern
   // (interactive nested in interactive), so we keep them peers and let
@@ -285,6 +289,23 @@ function CoverSlide({
         </div>
       </Link>
 
+      {/* Copy public link — a peer of the Link (no nested interactives). The
+          public route /c/<id> carries OG metadata so the pasted link unfurls
+          with a generated card. */}
+      <button
+        type="button"
+        onClick={() => copy(`${window.location.origin}/c/${c.id}`)}
+        aria-label={copied ? "Link copied" : "Copy collection link"}
+        title={copied ? "Link copied" : "Copy collection link"}
+        className={cn(
+          "absolute top-3 left-3 z-10 inline-flex size-8 items-center justify-center",
+          "rounded-full bg-black/50 backdrop-blur-sm hover:bg-black/70",
+          "text-white transition-colors",
+        )}
+      >
+        {copied ? <Check className="size-4" /> : <Link2 className="size-4" />}
+      </button>
+
       {onEdit ? (
         <button
           type="button"