Strip chat-ui to bundled-only: no public component exports

- Remove all chat-ui/simple exports and source (from p4)
- Remove chat-ui library export, build scripts (build:client-lib, build:chat-ui-simple)
- Remove library build configs (vite.lib.config.ts, tsconfig.lib.json, tailwind config)
- Move UI source back to client/src/ (no longer needed outside client bundle)
- Remove all React/UI peer deps and library-only dependencies
- Revert @/ alias and tsconfig paths to client-local ./src
- Simplify tsdown.config.ts to single server-only config
- Exclude src/chat-ui from main tsconfig (server-only type checking)
- Keep bundled UI app in dist/chat-client/ for chat.staticAssetsPath

Author: hubertzub-db

…agent/src/chat-ui/components/ChatApp.tsx …-agent/client/src/components/ChatApp.tsxintegrations/appkit-agent/src/chat-ui/components/ChatApp.tsx renamed to integrations/appkit-agent/client/src/components/ChatApp.tsx integrations/appkit-agent/src/chat-ui/components/ChatApp.tsx renamed to integrations/appkit-agent/client/src/components/ChatApp.tsx

@@ -1,8 +1,6 @@
 import { BrowserRouter, Routes, Route, useNavigate, useParams, useLocation } from 'react-router-dom';
-import { useState, useEffect, type ReactNode } from 'react';
+import { useState, useEffect } from 'react';
 import { Toaster } from 'sonner';
-import { ThemeProvider, useTheme as useNextTheme } from 'next-themes';
-import { ThemeContextProvider } from '@/contexts/ThemeContext';
 
 const LIGHT_THEME_COLOR = 'hsl(0 0% 100%)';
 const DARK_THEME_COLOR = 'hsl(240deg 10% 3.92%)';
@@ -46,28 +44,15 @@ export interface ChatAppProps extends Omit<ChatProviderProps, 'children'> {
  * sidebar, routing, and the complete chat experience. Renders a standalone
  * SPA that can be mounted into any container.
  */
-function NextThemesBridge({ children }: { children: ReactNode }) {
-  const { theme, resolvedTheme, setTheme } = useNextTheme();
-  return (
-    <ThemeContextProvider value={{ theme: theme ?? 'system', resolvedTheme: resolvedTheme ?? 'light', setTheme }}>
-      {children}
-    </ThemeContextProvider>
-  );
-}
-
 export function ChatApp({
   basePath = '/',
   ...providerProps
 }: ChatAppProps) {
   return (
     <BrowserRouter basename={basePath}>
       <ChatProvider basePath={basePath} {...providerProps}>
-        <ThemeProvider attribute="class" defaultTheme="system" enableSystem disableTransitionOnChange>
-          <NextThemesBridge>
-            <Toaster position="top-center" />
-            <ChatAppLayout />
-          </NextThemesBridge>
-        </ThemeProvider>
+        <Toaster position="top-center" />
+        <ChatAppLayout />
       </ChatProvider>
     </BrowserRouter>
   );