Add SVG flags for France, Hong Kong, Japan, South Korea, Russia, and the United States

- Added France flag (fr.svg) with three vertical stripes: blue, white, and red.
- Added Hong Kong flag (hk.svg) featuring a red background with a white flower emblem.
- Added Japan flag (jp.svg) with a white field and a red circle in the center.
- Added South Korea flag (kr.svg) showcasing a white background with a central yin-yang symbol and four black trigrams.
- Added Russia flag (ru.svg) with three horizontal stripes: white, blue, and red.
- Added United States flag (us.svg) with red and white stripes and a blue canton featuring stars.

templates/base.html

@@ -6,6 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1">
     <link rel="stylesheet" href="/loras_static/css/style.css">
     <link rel="stylesheet" href="/loras_static/css/onboarding.css">
+    <link rel="stylesheet" href="/loras_static/vendor/flag-icons/flag-icons.min.css">
     {% block page_css %}{% endblock %}
     <link rel="stylesheet" href="/loras_static/vendor/font-awesome/css/all.min.css"
         crossorigin="anonymous" referrerpolicy="no-referrer">