fix: pin Q API host to us-east-1, keep refresh URL per-region

feat: add --hello flag to test model connectivity

fix(tests): fix systemd --user not ready in Docker container

docs: sync README flow with actual code

feat: switch to user-level systemd, fix path expansion, harden tests

feat(install): grant executable permissions

docs: change YOUR_USERNAME -> FASTSHIFT

feat: interactive installer with systemd integration, tests, and CI

Initial commit