feat(root): add TIME_ZONE setting

Set timezone for Nepal to ensure correct datetime handling.

docker-compose.yml

@@ -35,6 +35,7 @@ services:
       DB_PASSWORD: ${DB_PASSWORD:-project_password}
       DB_HOST: db
       DB_PORT: ${DB_PORT:-3306}
+      TIME_ZONE: ${TIME_ZONE:-Asia/Kathmandu}
       BASE_URL: ${BASE_URL:-http://localhost:8000}
       SITE_NAME: ${SITE_NAME:-Project Management}
       FRONTEND_URL: ${FRONTEND_URL:-http://localhost:8000}