fix(auto): align agent launch with container shell

[skulidropek]

Summary

• run auto agents through the same effective bash/login shell path that works in the container manually
• replace the stale Codex auto invocation with codex exec
• pass DOCKER_GIT_PROJECTS_ROOT_HOST into docker compose so fresh nested issue workspaces mount the correct shared .docker-git root

Verification

• pnpm --filter ./packages/lib test -- packages/lib/tests/usecases/prepare-files.test.ts
• pnpm --filter ./packages/app test -- tests/docker-git/entrypoint-auth.test.ts
• pnpm check
• live demo: --claude --auto on issue Добавить установку из коробки этой библиотеки sshpass #119 created commit and PR feat(docker): add sshpass to container images #129, posted an issue comment, and cleaned up container on success

Notes

• failed agent runs still keep the container for debugging; success still triggers cleanup