UI polish pass: word count, slash commands, task lists, graph peek, bulk delete, export

- WordCount component (toggle words/chars vs read time, persisted mode)
- TipTap: TaskList/TaskItem extensions, slash command menu (H1-H3, lists, code, quote, task)
- Markdown serializer: task list → `- [ ]` / `- [x]` roundtrip
- GraphView: slide-in peek panel for note/task nodes (body, tags, linked nodes); tag nodes still navigate
- ChatView: bulk-select conversations with two-click confirm delete + chat retention policy (default 90d)
- NoteEditorView: pill tab bar with animated edit/preview toggle + WordCount in toolbar
- WorkspaceNoteEditor: inline search with tag matching, inline new-note creation, WordCount
- WorkspaceTaskPanel: task body rendered in slide-over + Edit link
- Settings: data export (Markdown ZIP / JSON) via GET /api/export
- Accessibility: skip-to-content link, aria-labels on all icon-only buttons
- Fix: export route used non-existent fabledassistant.database — corrected to async_session()
- Fix: ToolCallRecord.status type now includes "running" (was causing TS build error)
- Dockerfile: upgrade npm to latest before install to suppress major-version notice
- npm audit fix: patched minimatch (ReDoS) and rollup (path traversal) — 0 vulnerabilities

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/utils/markdownSerializer.ts

@@ -36,8 +36,15 @@ function serializeNode(node: JSONContent, listIndent = 0): string {
         (listIndent === 0 ? "\n" : "")
       );
 
+    case "taskList":
+      return (
+        serializeTaskList(node.content || [], listIndent) +
+        (listIndent === 0 ? "\n" : "")
+      );
+
     case "listItem":
-      // Handled by bulletList/orderedList
+    case "taskItem":
+      // Handled by their respective list serializers
       return "";
 
     case "codeBlock": {
@@ -106,6 +113,17 @@ function serializeOrderedList(
   return out;
 }
 
+function serializeTaskList(items: JSONContent[], indent: number): string {
+  let out = "";
+  for (const item of items) {
+    if (item.type !== "taskItem") continue;
+    const checked = item.attrs?.checked ? "x" : " ";
+    const prefix = "  ".repeat(indent) + `- [${checked}] `;
+    out += serializeListItem(item.content || [], prefix, indent);
+  }
+  return out;
+}
+
 function serializeListItem(
   children: JSONContent[],
   prefix: string,
@@ -131,6 +149,8 @@ function serializeListItem(
         indent + 1,
         child.attrs?.start ?? 1
       );
+    } else if (child.type === "taskList") {
+      out += serializeTaskList(child.content || [], indent + 1);
     } else {
       out += serializeNode(child, indent + 1);
     }