fix: resolve final workbench re-review findings

apps/web/src/features/workbench/channels/CustomLinkChannel.svelte

@@ -3,13 +3,22 @@
 
   export let channel: WorkbenchChannel;
   let copyStatus = '';
+  let copyFailed = false;
 
   async function copyUrl() {
+    if (!navigator.clipboard?.writeText) {
+      copyFailed = true;
+      copyStatus = 'Copy unavailable in this browser.';
+      return;
+    }
+
     try {
-      await navigator.clipboard?.writeText(channel.url ?? '');
+      await navigator.clipboard.writeText(channel.url ?? '');
+      copyFailed = false;
       copyStatus = 'URL copied.';
     } catch {
-      copyStatus = 'Copy unavailable in this browser.';
+      copyFailed = true;
+      copyStatus = 'Unable to copy URL.';
     }
   }
 </script>
@@ -20,6 +29,6 @@
   <a class="custom-link" href={channel.url} target="_blank" rel="noreferrer">Open external channel</a>
   <button class="copy-url-button" type="button" on:click={copyUrl}>Copy URL</button>
   {#if copyStatus}
-    <p class="copy-feedback" aria-live="polite">{copyStatus}</p>
+    <p class:copy-error={copyFailed} class="copy-feedback" aria-live="polite">{copyStatus}</p>
   {/if}
 </section>

apps/web/src/features/workbench/channels/CustomLinkChannel.test.ts

@@ -0,0 +1,36 @@
+import '@testing-library/jest-dom/vitest';
+import { cleanup, fireEvent, render, screen, waitFor } from '@testing-library/svelte';
+import { afterEach, describe, expect, it } from 'vitest';
+import CustomLinkChannel from './CustomLinkChannel.svelte';
+
+const channel = {
+  id: 'project-custom-link',
+  projectID: 1,
+  type: 'custom_link' as const,
+  title: 'Roadmap Board',
+  icon: 'link',
+  url: 'https://example.com/roadmap',
+  sortOrder: 1,
+};
+const originalClipboard = Object.getOwnPropertyDescriptor(navigator, 'clipboard');
+
+afterEach(() => {
+  cleanup();
+  if (originalClipboard) {
+    Object.defineProperty(navigator, 'clipboard', originalClipboard);
+  } else {
+    Reflect.deleteProperty(navigator, 'clipboard');
+  }
+});
+
+describe('CustomLinkChannel', () => {
+  it('reports unavailable clipboard access without showing URL copied', async () => {
+    Reflect.deleteProperty(navigator, 'clipboard');
+    render(CustomLinkChannel, { props: { channel } });
+
+    await fireEvent.click(screen.getByRole('button', { name: 'Copy URL' }));
+
+    await waitFor(() => expect(screen.getByText('Copy unavailable in this browser.')).toBeInTheDocument());
+    expect(screen.queryByText('URL copied.')).not.toBeInTheDocument();
+  });
+});