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/packages/chat-types/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "@chat/types",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "main": "./src/index.ts",
+  "types": "./src/index.ts",
+  "exports": {
+    ".": "./src/index.ts"
+  }
+}

chat/packages/chat-types/src/index.ts

@@ -0,0 +1,93 @@
+/**
+ * Chat Types - Shared type definitions for the Chat application
+ */
+
+// Message Types
+export interface ChatMessage {
+  role: 'system' | 'user' | 'assistant';
+  content: string;
+}
+
+export interface Message {
+  id: string;
+  conversation_id: string;
+  sender: 'user' | 'assistant' | 'system';
+  message_text: string;
+  created_at: string;
+  updated_at?: string;
+}
+
+// Conversation Types
+export interface Conversation {
+  id: string;
+  user_id: string;
+  model_id: string;
+  template_id?: string;
+  conversation_mode: 'free' | 'guided' | 'template';
+  document_mode: boolean;
+  title?: string;
+  is_archived: boolean;
+  created_at: string;
+  updated_at: string;
+}
+
+// AI Model Types
+export interface AIModelParameters {
+  temperature: number;
+  max_tokens: number;
+  provider: 'azure' | 'openai';
+  deployment: string;
+  endpoint: string;
+  api_version: string;
+}
+
+export interface AIModel {
+  id: string;
+  name: string;
+  description: string;
+  parameters: AIModelParameters;
+}
+
+// Token Usage Types
+export interface TokenUsage {
+  prompt_tokens: number;
+  completion_tokens: number;
+  total_tokens: number;
+}
+
+// API Response Types
+export interface ChatCompletionResponse {
+  content: string;
+  usage: TokenUsage;
+}
+
+// Template Types
+export interface Template {
+  id: string;
+  name: string;
+  description: string;
+  system_prompt: string;
+  created_at: string;
+  updated_at: string;
+}
+
+// Space Types
+export interface Space {
+  id: string;
+  name: string;
+  description?: string;
+  owner_id: string;
+  created_at: string;
+  updated_at: string;
+}
+
+// Document Types
+export interface Document {
+  id: string;
+  conversation_id: string;
+  title: string;
+  content: string;
+  version: number;
+  created_at: string;
+  updated_at: string;
+}