feat(chat): integrate chat project into monorepo with full app structure

- Restructure chat as apps/mobile, apps/web, apps/landing, backend
- Add NestJS backend for secure Azure OpenAI API calls
- Remove exposed API key from mobile app (security fix)
- Add shared chat-types package
- Create SvelteKit web app scaffold
- Create Astro landing page scaffold
- Update pnpm workspace configuration
- Add project-level CLAUDE.md documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

chat/apps/mobile/components/Button.tsx

@@ -0,0 +1,22 @@
+import { forwardRef } from 'react';
+import { Text, TouchableOpacity, TouchableOpacityProps, View } from 'react-native';
+
+type ButtonProps = {
+  title: string;
+} & TouchableOpacityProps;
+
+export const Button = forwardRef<View, ButtonProps>(({ title, ...touchableProps }, ref) => {
+  return (
+    <TouchableOpacity
+      ref={ref}
+      {...touchableProps}
+      className={`${styles.button} ${touchableProps.className}`}>
+      <Text className={styles.buttonText}>{title}</Text>
+    </TouchableOpacity>
+  );
+});
+
+const styles = {
+  button: 'items-center bg-indigo-500 rounded-[28px] shadow-md p-4',
+  buttonText: 'text-white text-lg font-semibold text-center',
+};