v0.6.0 — curated country groupings + country_group= on compare_countries

Adds analytical country groupings beyond WHO's built-in spatial dimensions, mirrored from ghed-mcp so a regional analysis behaves identically against either database.

What's new

• Curated groups in gho_mcp/country_groups.py:
  • World Bank geographic regions (FY2026): EAP (38), ECA (58), NAR (3), SAS (6), SSA (48), MENA (23 — now includes Afghanistan and Pakistan per WB's FY2026 reorganization)
  • LAC variants: LAC (33 sovereign states, PAHO/Decilion convention) vs LAC_TERRITORIES (42 with Caribbean territories)
  • MENA_EXCL_ISR_MLT (21)
  • LDC (44, UN Least Developed Countries verified 2026-05-06)
  • OECD (38)
• country_group= parameter on compare_countries — pass a curated code, get the right ISO3 list resolved through WHO's spatial dimensions in a single OData query. Merges with explicit countries= if both are supplied.
• Two new discovery tools: list_curated_country_groups and resolve_country_group_membership.
• Regional analysis section in the README — identical text to ghed-mcp for consistent capability framing.

World Bank FY2026 note

The World Bank reorganized regions effective July 2025. The old "Middle East & North Africa" region was renamed to "Middle East, North Africa, Afghanistan and Pakistan" — Afghanistan and Pakistan moved out of South Asia. We keep the alias MENA because that's the name health-systems literature still uses; the new 23-member composition is what it points at.

Bump rationale

SemVer at 0.x: minor for additive features. The new country_group= parameter and two new tools are public-API additions — minor (0.5.2 → 0.6.0).

See CHANGELOG.md for the full list.