Builder origin map #15

Why

Where builders come from is one of the first things people ask about an event.

In this repo today

linking/country.py already turns public profile locations into ISO country codes with pycountry, github_users.country stores the result, and /api/countries returns contributors per country for the Overview. What is missing is a hand curated alias list for strings pycountry misses, an explicit unknown bucket, and a map.

What to build

• config/locations.yaml: aliases for common profile strings, consulted before pycountry. No geocoder and no external calls. Unknown stays unknown.
• An explicit unknown bucket in the countries response.
• A small SVG world map component in apps/web/src/components/charts/ (a choropleth or dots, no map tiles) used in the Overview.

Acceptance criteria

• Tests in tests/test_country.py: "Lisbon, Portugal", "Lagos", "SF Bay Area" and "" normalize to PT, NG, US and unknown.
• The map renders with no network requests.

See CONTRIBUTING.md for conventions.