feat(notes): presence as avatar stack, drop guide lines, fix stuck bullet focus

- Leaving a block now clears its focus, so the bullet no longer stays highlighted
- Remove the vertical indentation guide lines
- Who has the note open: up to 3 overlapping avatars, "+n", full list on hover
- Shared AvatarStack component; UserAvatar gets xxs size and optional title

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

frontend/src/features/workspace/DocumentEditor.tsx

@@ -22,6 +22,7 @@ import { Document, DocumentBlock, User } from '../../lib/types';
 import { api } from '../../lib/api';
 import { DocSyncEngine, EngineState } from '../../lib/docSync/engine';
 import { OutlinerTree, OutlinerTreeHandle } from './OutlinerTree';
+import { PresenceAvatars } from './PresenceAvatars';
 import { extractHashtags } from '../../lib/hashtags';
 
 export type DocSaveStatus = 'saved' | 'saving' | 'unsaved' | 'error';
@@ -416,6 +417,22 @@ export const DocumentEditor: React.FC<DocumentEditorProps> = ({
     [engineState?.presence, currentUser?.id]
   );
 
+  // Presence only carries names; profile pictures come from the user directory, loaded once
+  // the first time someone else shows up (avatars can be data URLs, too big for every sync)
+  const [avatarsById, setAvatarsById] = useState<Map<string, string>>(new Map());
+  const avatarsRequestedRef = useRef(false);
+  useEffect(() => {
+    if (otherPeople.length === 0 || avatarsRequestedRef.current) return;
+    avatarsRequestedRef.current = true;
+    api.getUsersDirectory()
+      .then((users) => {
+        const m = new Map<string, string>();
+        for (const u of users) if (u.avatarUrl) m.set(u.id, u.avatarUrl);
+        setAvatarsById(m);
+      })
+      .catch(() => {});
+  }, [otherPeople.length]);
+
   // Short hint at the bottom of the editor (blocked actions, skipped undo)
   const [notice, setNotice] = useState<string | null>(null);
   const noticeTimerRef = useRef<number | null>(null);
@@ -816,15 +833,7 @@ export const DocumentEditor: React.FC<DocumentEditorProps> = ({
           )}
 
           {/* Who else has this note open */}
-          {otherPeople.length > 0 && (
-            <span
-              className="hidden sm:inline-flex items-center gap-1 px-2 py-0.5 rounded-btn text-[11px] text-muted bg-panel border border-border"
-              title="Hat diese Notiz gerade geöffnet"
-            >
-              <Users className="w-3 h-3 text-accent" />
-              {otherPeople.map((p) => p.name).join(', ')}
-            </span>
-          )}
+          <PresenceAvatars people={otherPeople} avatars={avatarsById} />
           {/* Sharing Section */}
           {doc && (() => {
             const isOwner = doc.isOwner !== false && (doc.userId === currentUser?.id || !doc.userId || currentUser?.role === 'admin');