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/HistoryPanel.vue

@@ -114,7 +114,7 @@ onMounted(loadVersions);
       <div class="modal-card history-modal">
         <div class="history-header">
           <h3 class="history-title">Version History</h3>
-          <button class="history-close" @click="emit('close')">&times;</button>
+          <button class="history-close" aria-label="Close version history" @click="emit('close')">&times;</button>
         </div>
 
         <div class="history-body">