This site is built in phases (foundation → expansion → maturity → authority). The schedule
lives in _plan/PHASE_PLAN.md.
To upgrade: read _plan/PHASE_PLAN.md, build the Next phase it names by adding pages and
applying the page blueprint to everything you touch, then record it from the Django project:
.venv/bin/python manage.py set_site_phase internal-developer-portal.com --completed <phase>.