feat: add list/upload flag UI

frontend/src/routes/settings/flags/Flag.svelte

@@ -0,0 +1,20 @@
+<script lang="ts">
+  import { flagURL, type PrideFlag } from "$lib/api/entities";
+  import { Button } from "sveltestrap";
+
+  export let flag: PrideFlag;
+</script>
+
+<Button outline class="m-1">
+  <img class="flag" src={flagURL(flag)} alt={flag.description ?? flag.name} />
+  {flag.name}
+</Button>
+
+<style>
+  .flag {
+    height: 2rem;
+    max-width: 200px;
+    border-radius: 3px;
+    margin-left: -5px;
+  }
+</style>