feat: chatbot

frontend/src/App.tsx

@@ -37,6 +37,7 @@ import MacroSeriesPage from './pages/MacroSeriesPage'
 import EuroSimulator from './pages/EuroSimulator'
 import CausalLab from './pages/CausalLab'
 import InstrumentModels from './pages/InstrumentModels'
+import ChatWidget from './components/ChatWidget'
 import { useCycleWatcher } from './hooks/useApi'
 
 // ── Keep-alive pages ──────────────────────────────────────────────────────────
@@ -157,6 +158,7 @@ function AppInner() {
   return (
     <div className="flex h-screen overflow-hidden">
       <GlobalWatcher />
+      <ChatWidget />
       <Sidebar />
       <div className="flex-1 flex flex-col min-h-0 overflow-hidden">
         <TabBar />