register all cron jobs in entrypoint (#12791)

closes https://github.com/twentyhq/core-team-issues/issues/1113

Three things I am not sure about - 
- Should we have a variable just like DISABLE_DB_MIGRATIONS to control
cron job registration behavior, i.e., DISABLE_CRON_JOBS_REGISTRATION?
- The location of the command ie, folder placement
- https://github.com/twentyhq/twenty/pull/12791/files#r2161734131

packages/twenty-docker/twenty/entrypoint.sh

@@ -28,7 +28,23 @@ setup_and_migrate_db() {
     yarn command:prod upgrade
     echo "Successfully migrated DB!"
 }
+
+register_background_jobs() {
+    if [ "${DISABLE_CRON_JOBS_REGISTRATION}" = "true" ]; then
+        echo "Cron job registration is disabled, skipping..."
+        return
+    fi
+  
+    echo "Registering background sync jobs..."
+    if yarn command:prod cron:register:all; then
+        echo "Successfully registered all background sync jobs!"
+    else
+        echo "Warning: Failed to register background jobs, but continuing startup..."
+    fi
+}
+
 setup_and_migrate_db
+register_background_jobs
 
 # Continue with the original Docker command
 exec "$@"