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/components/TiptapEditor.vue

@@ -7,9 +7,12 @@ import Placeholder from "@tiptap/extension-placeholder";
 import { marked } from "marked";
 import DOMPurify from "dompurify";
 import { serializeToMarkdown } from "@/utils/markdownSerializer";
+import TaskList from "@tiptap/extension-task-list";
+import TaskItem from "@tiptap/extension-task-item";
 import { TagDecoration } from "@/extensions/TagDecoration";
 import { WikilinkDecoration } from "@/extensions/WikilinkDecoration";
 import { WikilinkSuggestion } from "@/extensions/WikilinkSuggestion";
+import { SlashCommands } from "@/extensions/SlashCommands";
 
 const props = withDefaults(
   defineProps<{
@@ -76,9 +79,12 @@ try {
       Placeholder.configure({
         placeholder: props.placeholder,
       }),
+      TaskList,
+      TaskItem.configure({ nested: true }),
       TagDecoration,
       WikilinkDecoration,
       WikilinkSuggestion,
+      SlashCommands,
     ],
     onUpdate({ editor: ed }) {
       if (updatingFromProp) return;