Stage 8: world map view — backend endpoint, map component, map page

- BansByCountryResponse model added to ban.py
- bans_by_country() service: parallel geo lookup via asyncio.gather,
  aggregation by ISO alpha-2 country code (up to 2 000 bans)
- GET /api/dashboard/bans/by-country endpoint in dashboard router
- 290 tests pass (5 new), ruff + mypy clean (44 files)
- isoNumericToAlpha2.ts: 249-entry ISO numeric → alpha-2 static map
- types/map.ts, api/map.ts, hooks/useMapData.ts created
- WorldMap.tsx: react-simple-maps Mercator SVG map, per-country ban
  count overlay, colour intensity scaling, country click filtering,
  GeoLayer nested-component pattern for useGeographies context
- MapPage.tsx: time-range selector, WorldMap, country filter info bar,
  summary line, companion FluentUI Table with country filter
- Frontend tsc + ESLint clean (0 errors/warnings)

frontend/package.json

@@ -15,9 +15,11 @@
   "dependencies": {
     "@fluentui/react-components": "^9.55.0",
     "@fluentui/react-icons": "^2.0.257",
+    "@types/react-simple-maps": "^3.0.6",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
-    "react-router-dom": "^6.27.0"
+    "react-router-dom": "^6.27.0",
+    "react-simple-maps": "^3.0.0"
   },
   "devDependencies": {
     "@eslint/js": "^9.13.0",