refactor(ui): rename route /korrespondenz → /briefwechsel

Update all internal links (AppNav, CoCorrespondentsList, goto) to the
new URL. No redirect needed — no production URLs exist yet.

Refs: #179

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/briefwechsel/CorrespondentSuggestionsDropdown.svelte

@@ -0,0 +1,100 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+import { clickOutside } from '$lib/actions/clickOutside';
+
+interface Correspondent {
+	id: string;
+	firstName: string;
+	lastName: string;
+}
+
+interface Props {
+	correspondents: Correspondent[];
+	loading: boolean;
+	senderName: string;
+	onselect: (id: string) => void;
+	onclose: () => void;
+}
+
+let { correspondents, loading, senderName, onselect, onclose }: Props = $props();
+
+function getOptionElements(container: HTMLElement): HTMLElement[] {
+	return Array.from(container.querySelectorAll<HTMLElement>('[role="option"]'));
+}
+
+function handleKeydown(event: KeyboardEvent, container: HTMLElement) {
+	const options = getOptionElements(container);
+	const focused = document.activeElement as HTMLElement;
+	const idx = options.indexOf(focused);
+
+	if (event.key === 'ArrowDown') {
+		event.preventDefault();
+		const next = options[idx + 1] ?? options[0];
+		next?.focus();
+	} else if (event.key === 'ArrowUp') {
+		event.preventDefault();
+		const prev = options[idx - 1] ?? options[options.length - 1];
+		prev?.focus();
+	} else if (event.key === 'Escape') {
+		onclose();
+	}
+}
+
+function getInitials(person: Correspondent): string {
+	return `${person.firstName.charAt(0)}${person.lastName.charAt(0)}`.toUpperCase();
+}
+</script>
+
+<div
+	use:clickOutside
+	onclickoutside={onclose}
+	role="listbox"
+	tabindex="-1"
+	aria-label={m.conv_suggestions_heading()}
+	class="absolute top-full right-0 left-0 z-30 mt-1 rounded-sm border border-line bg-surface shadow-lg"
+	onkeydown={(e) => handleKeydown(e, e.currentTarget as HTMLElement)}
+>
+	<!-- Heading -->
+	<div class="px-3 pt-2 pb-1 text-[10px] font-bold tracking-widest text-ink-3 uppercase">
+		{m.conv_suggestions_heading()}
+	</div>
+
+	<!-- Correspondent rows -->
+	{#if !loading}
+		{#each correspondents as person (person.id)}
+			<div
+				role="option"
+				aria-selected="false"
+				tabindex="0"
+				class="flex cursor-pointer items-center gap-2 px-3 py-2 text-sm text-ink hover:bg-muted focus:bg-muted focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring focus-visible:ring-inset"
+				onclick={() => onselect(person.id)}
+				onkeydown={(e) => e.key === 'Enter' && onselect(person.id)}
+			>
+				<!-- Avatar with initials -->
+				<span
+					class="flex h-4 w-4 shrink-0 items-center justify-center rounded-full bg-primary text-[10px] font-bold text-primary-fg"
+					aria-hidden="true"
+				>
+					{getInitials(person)}
+				</span>
+				<!-- Svelte auto-escapes — do not use {@html} here. -->
+				{person.lastName}, {person.firstName}
+			</div>
+		{/each}
+	{/if}
+
+	<!-- Separator -->
+	<div class="mt-1 border-t border-line"></div>
+
+	<!-- "Alle Korrespondenten" row -->
+	<div
+		role="option"
+		aria-selected="false"
+		tabindex="0"
+		class="flex cursor-pointer items-center gap-2 px-3 py-2 text-sm text-ink hover:bg-muted focus:bg-muted focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring focus-visible:ring-inset"
+		onclick={() => onselect('')}
+		onkeydown={(e) => e.key === 'Enter' && onselect('')}
+	>
+		{m.conv_suggestions_all_label({ name: senderName })}
+	</div>
+</div>