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)

backend/app/routers/dashboard.py

@@ -20,6 +20,7 @@ from fastapi import APIRouter, Query, Request
 from app.dependencies import AuthDep
 from app.models.ban import (
     AccessListResponse,
+    BansByCountryResponse,
     DashboardBanListResponse,
     TimeRange,
 )
@@ -156,3 +157,41 @@ async def get_dashboard_accesses(
         geo_enricher=_enricher,
     )
 
+
+@router.get(
+    "/bans/by-country",
+    response_model=BansByCountryResponse,
+    summary="Return ban counts aggregated by country",
+)
+async def get_bans_by_country(
+    request: Request,
+    _auth: AuthDep,
+    range: TimeRange = Query(default=_DEFAULT_RANGE, description="Time-range preset."),
+) -> BansByCountryResponse:
+    """Return ban counts aggregated by ISO country code.
+
+    Fetches up to 2 000 ban records in the selected time window, enriches
+    every record with geo data, and returns a ``{country_code: count}`` map
+    plus the full enriched ban list for the companion access table.
+
+    Args:
+        request: The incoming request.
+        _auth: Validated session dependency.
+        range: Time-range preset.
+
+    Returns:
+        :class:`~app.models.ban.BansByCountryResponse` with per-country
+        aggregation and the full ban list.
+    """
+    socket_path: str = request.app.state.settings.fail2ban_socket
+    http_session: aiohttp.ClientSession = request.app.state.http_session
+
+    async def _enricher(ip: str) -> geo_service.GeoInfo | None:
+        return await geo_service.lookup(ip, http_session)
+
+    return await ban_service.bans_by_country(
+        socket_path,
+        range,
+        geo_enricher=_enricher,
+    )
+