refactor: migrate API from Apollo Server to Mercurius and enhance GraphQL implementation

- Replaced Apollo Server with Mercurius for GraphQL API
- Updated resolvers to use Mercurius-compatible GraphQL implementation
- Migrated from Express to Fastify for server framework
- Improved error handling with GraphQL error extensions
- Added Zod for environment variable validation
- Updated Prisma schema and migrations
- Configured CORS and WebSocket subscriptions
- Simplified GraphQL schema and resolver structure
- Enhanced type safety and code organization

apps/web/src/lib/graphql-client.ts

@@ -1,16 +1,20 @@
+import { z } from 'zod';
 import { createClient, fetchExchange, subscriptionExchange } from '@urql/core';
-import { createClient as createWSClient } from 'graphql-ws';
+import { createClient as createWsClient } from 'graphql-ws';
 
 // Get API URLs from environment variables
-const API_URL =
-  import.meta.env.VITE_API_URL || 'https://chat-api.jusemon.com/graphql';
-const WS_URL =
-  import.meta.env.VITE_WS_URL || 'wss://chat-api.jusemon.com/graphql';
+const envSchema = z
+  .object({ VITE_API_URL: z.string(), VITE_WS_URL: z.string() })
+  .transform((env) => ({
+    API_URL: env.VITE_API_URL,
+    WS_URL: env.VITE_WS_URL,
+  }));
+const { API_URL, WS_URL } = envSchema.parse(import.meta.env);
 console.log('Current API_URL', API_URL);
 console.log('Current WS_URL', WS_URL);
 
 // Create a WebSocket client for GraphQL subscriptions
-const wsClient = createWSClient({
+const wsClient = createWsClient({
   url: WS_URL,
 });
 
@@ -23,11 +27,8 @@ export const client = createClient({
       forwardSubscription: (operation) => ({
         subscribe: (sink) => {
           const dispose = wsClient.subscribe(
-            {
-              ...operation,
-              query: operation.query || '',
-            },
-            sink as any
+            { ...operation, query: operation.query || '' },
+            sink
           );
           return {
             unsubscribe: dispose,