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/models/ban.py

@@ -191,3 +191,29 @@ class AccessListResponse(BaseModel):
     total: int = Field(..., ge=0)
     page: int = Field(..., ge=1)
     page_size: int = Field(..., ge=1)
+
+
+class BansByCountryResponse(BaseModel):
+    """Response for the bans-by-country aggregation endpoint.
+
+    Contains a per-country ban count, a human-readable country name map, and
+    the full (un-paginated) ban list for the selected time window so the
+    frontend can render both the world map and its companion table from a
+    single request.
+    """
+
+    model_config = ConfigDict(strict=True)
+
+    countries: dict[str, int] = Field(
+        default_factory=dict,
+        description="ISO 3166-1 alpha-2 country code → ban count.",
+    )
+    country_names: dict[str, str] = Field(
+        default_factory=dict,
+        description="ISO 3166-1 alpha-2 country code → human-readable country name.",
+    )
+    bans: list[DashboardBanItem] = Field(
+        default_factory=list,
+        description="All bans in the selected time window (up to the server limit).",
+    )
+    total: int = Field(..., ge=0, description="Total ban count in the window.")