perf: bundle flag icons instead of blocking on a CDN (#99)

index.html loaded two jsdelivr stylesheets synchronously in <head>, which
delayed first paint and failed outright on networks where the CDN is
unreachable. Drop font-logos (unused in src/) and bundle flag-icons
locally so Vite hashes the sprites and serves them from our own origin
with immutable cache headers.

package.json

@@ -50,6 +50,7 @@
 		"country-flag-icons": "1.6.17",
 		"d3-geo": "3.1.1",
 		"dayjs": "1.11.21",
+		"flag-icons": "7.0.0",
 		"i18n-iso-countries": "7.14.0",
 		"i18next": "26.3.1",
 		"lucide-react": "1.17.0",