v1.8.1 Patchfix: add e5e2 support and default to hybrid for Launcher

AI Impact Summary

v1.8.1 adds native support for the e5e2 model and makes hybrid the default mode when the Launcher is invoked. This reduces manual configuration for deployments using the Launcher and unlocks e5e2 capabilities without code changes. Teams should verify that Launcher-driven workflows select e5e2 by default and test for any mode-related regressions across shards referenced in #3640 and #3645.