Initial implementation of vault-os

Complete implementation across all 13 phases:

- vault-core: types, YAML frontmatter parsing, entity classification,
  filesystem ops, config, prompt composition, validation, search
- vault-watch: filesystem watcher with daemon write filtering, event
  classification
- vault-scheduler: cron engine, process executor, task runner with
  retry logic and concurrency limiting
- vault-api: Axum REST API (15 route modules), WebSocket with broadcast,
  AI assistant proxy, validation, templates
- Dashboard: React + TypeScript + Tailwind v4 with kanban, CodeMirror
  editor, dynamic view system, AI chat sidebar
- Nix flake with dev shell and NixOS module
- Graceful shutdown, inotify overflow recovery, tracing instrumentation

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

dashboard/src/App.tsx

@@ -0,0 +1,47 @@
+import { BrowserRouter, Routes, Route } from 'react-router-dom';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { Layout } from './components/Layout';
+import { TasksPage } from './pages/TasksPage';
+import { AgentsPage } from './pages/AgentsPage';
+import { CronsPage } from './pages/CronsPage';
+import { AgentQueuePage } from './pages/AgentQueuePage';
+import { KnowledgePage } from './pages/KnowledgePage';
+import { EditorPage } from './pages/EditorPage';
+import { ViewPage } from './pages/ViewPage';
+import { CommandPalette } from './components/CommandPalette';
+import { useWebSocket } from './hooks/useWebSocket';
+
+const queryClient = new QueryClient({
+  defaultOptions: {
+    queries: { staleTime: 5000, retry: 1 },
+  },
+});
+
+function AppInner() {
+  useWebSocket();
+
+  return (
+    <BrowserRouter>
+      <CommandPalette />
+      <Routes>
+        <Route element={<Layout />}>
+          <Route path="/" element={<TasksPage />} />
+          <Route path="/agents" element={<AgentsPage />} />
+          <Route path="/crons" element={<CronsPage />} />
+          <Route path="/queue" element={<AgentQueuePage />} />
+          <Route path="/knowledge" element={<KnowledgePage />} />
+          <Route path="/editor" element={<EditorPage />} />
+          <Route path="/view/*" element={<ViewPage />} />
+        </Route>
+      </Routes>
+    </BrowserRouter>
+  );
+}
+
+export default function App() {
+  return (
+    <QueryClientProvider client={queryClient}>
+      <AppInner />
+    </QueryClientProvider>
+  );
+}