fix(geoportal): fullscreen route + local CSS + proper layout

- Add /geoportal to FULLSCREEN_ROUTES (overflow-hidden, no padding)
- Copy maplibre-gl.css to public/ and load from same origin (avoids CDN/CSP)
- Simplify layout: fill parent via h-full w-full (no negative margin hack)

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

src/shared/components/layout/app-shell.tsx

@@ -10,7 +10,7 @@ import { cn } from '@/shared/lib/utils';
 const SIDEBAR_COLLAPSED_KEY = 'sidebar:collapsed';
 
 // Routes that need full viewport height and no padding (canvas tools)
-const FULLSCREEN_ROUTES = ['/visual-copilot'];
+const FULLSCREEN_ROUTES = ['/visual-copilot', '/geoportal'];
 
 interface AppShellProps {
   children: React.ReactNode;