fix(a11y): 44px remove targets + empty states on person/document pickers

Both PersonMultiSelect and DocumentMultiSelect remove buttons were ~12px tap
targets (below the 44px WCAG minimum) — pad them to min-h/min-w 44px with a
focus-visible ring (SVG stays 12px). Add an optional emptyLabel slot inside the
chip container and a hiddenInputName prop on PersonMultiSelect (mirroring
DocumentMultiSelect) so EventForm can wire personIds without touching
WhoWhenSection. Document the intentional bare typeahead fetch in
documentTypeahead.ts (same-origin in prod, Vite-proxied in dev).

Refs #781
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/document/DocumentMultiSelect.svelte

@@ -11,12 +11,15 @@ interface Props {
 	selectedDocuments?: DocumentOption[];
 	placeholder?: string;
 	hiddenInputName?: string;
+	/** Empty-state text shown inside the chip container when nothing is selected. */
+	emptyLabel?: string;
 }
 
 let {
 	selectedDocuments = $bindable([]),
 	placeholder = m.geschichte_editor_search_document(),
-	hiddenInputName = 'documentIds'
+	hiddenInputName = 'documentIds',
+	emptyLabel = undefined
 }: Props = $props();
 
 let searchTerm = $state('');
@@ -73,7 +76,7 @@ function removeDocument(id: string | undefined) {
 				<button
 					type="button"
 					onclick={() => removeDocument(doc.id)}
-					class="ml-0.5 text-ink/50 hover:text-red-500 focus:outline-none"
+					class="ml-0.5 inline-flex min-h-[44px] min-w-[44px] items-center justify-center rounded-sm text-ink/50 hover:text-red-500 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
 					aria-label={m.comp_multiselect_remove()}
 				>
 					<svg class="h-3 w-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -88,6 +91,10 @@ function removeDocument(id: string | undefined) {
 			</span>
 		{/each}
 
+		{#if emptyLabel && selectedDocuments.length === 0}
+			<span class="px-1 py-1 font-sans text-sm text-ink-3 italic">{emptyLabel}</span>
+		{/if}
+
 		<input
 			bind:this={inputEl}
 			type="text"

frontend/src/lib/document/documentTypeahead.ts

@@ -12,6 +12,10 @@ export type DocumentOption = Pick<
 
 export function createDocumentTypeahead() {
 	return createTypeahead<DocumentOption>({
+		// Intentional bare browser fetch (matches the Geschichte editor): in dev the
+		// Vite proxy forwards /api and injects the auth header; in prod the app is
+		// same-origin so the auth cookie travels automatically. An internal
+		// +server.ts proxy would add complexity with no practical security benefit.
 		fetchUrl: (q) =>
 			fetch(`/api/documents/search?q=${encodeURIComponent(q)}&size=10`)
 				.then((r) => {

frontend/src/lib/person/PersonMultiSelect.svelte

@@ -7,9 +7,17 @@ type Person = components['schemas']['Person'];
 
 interface Props {
 	selectedPersons?: PersonOption[];
+	/** Name of the hidden inputs carrying selected ids. Mirrors DocumentMultiSelect. */
+	hiddenInputName?: string;
+	/** Empty-state text shown inside the chip container when nothing is selected. */
+	emptyLabel?: string;
 }
 
-let { selectedPersons = $bindable([]) }: Props = $props();
+let {
+	selectedPersons = $bindable([]),
+	hiddenInputName = 'receiverIds',
+	emptyLabel = undefined
+}: Props = $props();
 
 let searchTerm = $state('');
 let results: Person[] = $state([]);
@@ -64,7 +72,7 @@ function removePerson(id: string | undefined) {
 <svelte:window onscroll={updateDropdownPosition} onresize={updateDropdownPosition} />
 
 {#each selectedPersons as person (person.id)}
-	<input type="hidden" name="receiverIds" value={person.id} />
+	<input type="hidden" name={hiddenInputName} value={person.id} />
 {/each}
 
 <div class="relative" use:clickOutside onclickoutside={() => (showDropdown = false)}>
@@ -79,7 +87,7 @@ function removePerson(id: string | undefined) {
 				<button
 					type="button"
 					onclick={() => removePerson(person.id)}
-					class="ml-0.5 text-ink/50 hover:text-red-500 focus:outline-none"
+					class="ml-0.5 inline-flex min-h-[44px] min-w-[44px] items-center justify-center rounded-sm text-ink/50 hover:text-red-500 focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
 					aria-label={m.comp_multiselect_remove()}
 				>
 					<svg class="h-3 w-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
@@ -94,6 +102,10 @@ function removePerson(id: string | undefined) {
 			</span>
 		{/each}
 
+		{#if emptyLabel && selectedPersons.length === 0}
+			<span class="px-1 py-1 font-sans text-sm text-ink-3 italic">{emptyLabel}</span>
+		{/if}
+
 		<input
 			bind:this={inputEl}
 			type="text"