fix(ux): Batch D part 2 — Marketplace in the nav; Clink fallback copy

- Add Marketplace to the More menu (it had no primary-nav entry)
- CLINK: explain the copy/QR fallback when no CLINK-compatible wallet handles
  the deep link, so 'Open in CLINK wallet' is not a silent no-op

src/components/ClinkPayButton.tsx

@@ -196,8 +196,9 @@ export function ClinkPayButton({
             <p className="flex items-start gap-1.5 text-center text-xs text-muted-foreground">
               <ShieldCheck className="mt-0.5 h-3.5 w-3.5 shrink-0 text-indigo-500" />
               <span>
-                Scan with a CLINK-compatible wallet (e.g. ShockWallet). No custodian,
-                no web server — the invoice is requested directly over Nostr.
+                Scan with a CLINK-compatible wallet (e.g. ShockWallet). If nothing opens, copy the
+                code above — you may not have a CLINK-compatible wallet installed. No custodian,
+                no web server: the invoice is requested directly over Nostr.
               </span>
             </p>
           </div>

src/components/Layout.tsx

@@ -237,6 +237,12 @@ function MobileHeaderUserMenu({
             <span className="text-[#ccff00]">Leaderboards</span>
           </Link>
         </DropdownMenuItem>
+        <DropdownMenuItem asChild>
+          <Link to="/marketplace" className="flex items-center gap-2 cursor-pointer">
+            <Package className="h-4 w-4 text-orange-400" />
+            <span className="text-orange-400">Marketplace</span>
+          </Link>
+        </DropdownMenuItem>
 
         {/* ── Accounts: switch between logged-in npubs + add another ── */}
         <DropdownMenuSeparator />