feat(workspace): link previews above bullets with a web address (M5)

- GET /link-preview?url= fetches the page on the server (https only,
  SSRF-guarded like webhooks), reads Open Graph/Twitter tags, title,
  description and icon from the head, loads picture and icon (no SVG) and
  keeps them in link_previews (migration 6) for 7 days; readers' browsers
  never contact the page. Off in the demo; 300 fetches per address in
  15 minutes.
- Compact card above the bullet (icon, site, title, one line, small
  picture); the duplicate link badge is left out.
- ✕ turns the address into [title](url), so hiding syncs with the note;
  "Link-Vorschauen anzeigen" under appearance switches all off per device.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/workspace/OutlinerBlock.tsx

@@ -33,6 +33,8 @@ import { AudioRecorderPicker } from './AudioRecorderPicker';
 import { AudioBlock } from './AudioBlock';
 import { DictationBlock } from './DictationBlock';
 import { currentVoiceConfig } from '../../lib/voice';
+import { LinkPreviewCard } from './LinkPreviewCard';
+import { firstBareUrl, hidePreviewContent, useLinkPreviewsEnabled } from '../../lib/linkPreview';
 import { mediaContent, parseMediaContent } from '../../lib/media';
 import { renderInlineMarkdown } from '../../lib/markdown';
 import { api } from '../../lib/api';
@@ -153,6 +155,12 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
   const [slashSearch, setSlashSearch] = useState<string | null>(null);
   // Inline picker an empty bullet turns into after /image (local only, nothing synced until done)
   const [mediaPicker, setMediaPicker] = useState<'image' | 'audio' | 'dictation' | null>(null);
+  // Card above bullets with a plain web address (lib/linkPreview.ts)
+  const previewsOn = useLinkPreviewsEnabled();
+  const previewUrl =
+    previewsOn && !mediaPicker && ['bullet', 'text', 'paragraph', 'todo', 'h1', 'h2', 'h3'].includes(block.type || 'bullet')
+      ? firstBareUrl(localContent)
+      : null;
   const [slashIndex, setSlashIndex] = useState(0);
   const [showLinkModal, setShowLinkModal] = useState<boolean>(false);
   const [showTodoMenu, setShowTodoMenu] = useState<boolean>(false);
@@ -749,7 +757,7 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
     (t) =>
       (t.startsWith('[[') && t.endsWith(']]')) ||
       /^\[(.*?)\]\((https?:\/\/.*?)\)$/.test(t) ||
-      /^https?:\/\//.test(t)
+      (/^https?:\/\//.test(t) && t !== previewUrl)
   );
 
   return (
@@ -851,6 +859,18 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
 
       {/* Main Block Content */}
       <div className="flex-1 min-w-0 pr-1 relative min-h-[1.5rem]">
+        {previewUrl && (
+          <LinkPreviewCard
+            url={previewUrl}
+            canEdit={canEdit}
+            onHide={(title) => {
+              const content = hidePreviewContent(localContent, previewUrl, title);
+              setLocalContent(content);
+              localContentRef.current = content;
+              flushDebounce(content);
+            }}
+          />
+        )}
         {mediaPicker === 'image' ? (
           <ImagePicker
             docId={docId}
@@ -1193,7 +1213,8 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
                   </a>
                 );
               }
-              if (/^https?:\/\//.test(part) && safeHref(part)) {
+              // The preview card above already shows this address
+              if (/^https?:\/\//.test(part) && safeHref(part) && part !== previewUrl) {
                 return (
                   <a
                     key={idx}