feat: add military bases map layer for Western Pacific

Add 18 US military bases (Japan, Guam, South Korea, Hawaii, Diego Garcia)
as a toggleable map layer. Follows the existing data center layer pattern:
static JSON → backend fetcher → slow-tier API → frontend GeoJSON layer.

Includes red circle markers with labels, click popups showing operator
and branch info, and a toggle in the left panel.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/WorldviewLeftPanel.tsx

@@ -147,6 +147,7 @@ const WorldviewLeftPanel = React.memo(function WorldviewLeftPanel({ data, active
         { id: "firms", name: "Fire Hotspots (24h)", source: "NASA FIRMS VIIRS", count: data?.firms_fires?.length || 0, icon: Flame },
         { id: "internet_outages", name: "Internet Outages", source: "IODA / Georgia Tech", count: data?.internet_outages?.length || 0, icon: Wifi },
         { id: "datacenters", name: "Data Centers", source: "DC Map (GitHub)", count: data?.datacenters?.length || 0, icon: Server },
+        { id: "military_bases", name: "Military Bases", source: "OSINT (Static)", count: data?.military_bases?.length || 0, icon: Shield },
         { id: "day_night", name: "Day / Night Cycle", source: "Solar Calc", count: null, icon: Sun },
     ];