Updated packages. Changed date picker package to Day.JS and applied it across whole app.

backend/src/core/plugins/error.plugin.ts

@@ -2,12 +2,12 @@
  * @ai-summary Fastify global error handling plugin
  * @ai-context Handles uncaught errors with structured logging
  */
-import { FastifyPluginAsync } from 'fastify';
+import { FastifyPluginAsync, FastifyError } from 'fastify';
 import fp from 'fastify-plugin';
 import { logger } from '../logging/logger';
 
 const errorPlugin: FastifyPluginAsync = async (fastify) => {
-  fastify.setErrorHandler((error, request, reply) => {
+  fastify.setErrorHandler((error: FastifyError, request, reply) => {
     logger.error('Unhandled error', {
       error: error.message,
       stack: error.stack,