**Motivations:**
- Single generic orchestration in ia_dev while business logic stays in each project repo
**Root causes:**
- N/A (evolution)
**Correctifs:**
- N/A
**Evolutions:**
- Add orchestrator.sh (deploy.hooks.phases or fallback deploy.deploy_script_path)
- Add deploy.sh <project_id> <env> [options] as canonical entry from ia_dev root
- run-project-hooks.sh execs orchestrator.sh for backward compatibility
- change-to-all-branches.sh and deploy-by-script-to.sh invoke orchestrator.sh when IA_PROJECT_ID is set
- Document orchestration in README.md and deploy/lib/README.md
**Pages affectées:**
- README.md, deploy/orchestrator.sh, deploy/deploy.sh, deploy/run-project-hooks.sh, deploy/change-to-all-branches.sh, deploy/deploy-by-script-to.sh, deploy/lib/README.md