fix(bulk-upload): i18n hardcoded strings in BulkDropZone and FileSwitcherStrip

- Add bulk_drop_desc, bulk_select_files, bulk_drop_zone_label, bulk_remove_file
  keys to de/en/es message files
- BulkDropZone: use m.bulk_drop_zone_label(), m.bulk_drop_desc(),
  m.bulk_select_files() — removes all hardcoded German
- FileSwitcherStrip: use m.bulk_remove_file() on × button; move aria-live
  from <ul> to a dedicated visually-hidden region above the strip (screen
  readers now announce changes without coupling the live region to the list)
- Spec: import FileEntry from component instead of re-declaring; use
  data-remove-id selector instead of hardcoded German aria-label

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

frontend/messages/de.json

@@ -868,5 +868,9 @@
 	"bulk_file_error_chip_label": "Fehler beim Hochladen",
 	"bulk_upload_progress": "{done} von {total} hochgeladen",
 	"bulk_partial_success": "{created} erstellt, {failed} fehlgeschlagen",
-	"bulk_all_failed": "Alle Uploads fehlgeschlagen"
+	"bulk_all_failed": "Alle Uploads fehlgeschlagen",
+	"bulk_drop_desc": "Für jede Datei wird ein eigenes Dokument erstellt. Der Titel wird aus dem Dateinamen vorausgefüllt — alle anderen Felder gelten für alle gemeinsam.",
+	"bulk_select_files": "Dateien auswählen",
+	"bulk_drop_zone_label": "Dateien ablegen",
+	"bulk_remove_file": "Entfernen"
 }

frontend/messages/en.json

@@ -868,5 +868,9 @@
 	"bulk_file_error_chip_label": "Upload failed",
 	"bulk_upload_progress": "{done} of {total} uploaded",
 	"bulk_partial_success": "{created} created, {failed} failed",
-	"bulk_all_failed": "All uploads failed"
+	"bulk_all_failed": "All uploads failed",
+	"bulk_drop_desc": "A separate document is created for each file. The title is pre-filled from the filename — all other fields apply to all documents.",
+	"bulk_select_files": "Select files",
+	"bulk_drop_zone_label": "Drop files here",
+	"bulk_remove_file": "Remove"
 }

frontend/messages/es.json

@@ -868,5 +868,9 @@
 	"bulk_file_error_chip_label": "Error al subir",
 	"bulk_upload_progress": "{done} de {total} subidos",
 	"bulk_partial_success": "{created} creados, {failed} fallidos",
-	"bulk_all_failed": "Todos los uploads fallaron"
+	"bulk_all_failed": "Todos los uploads fallaron",
+	"bulk_drop_desc": "Se crea un documento separado por archivo. El título se rellena desde el nombre del archivo — el resto de campos se aplican a todos.",
+	"bulk_select_files": "Seleccionar archivos",
+	"bulk_drop_zone_label": "Soltar archivos aquí",
+	"bulk_remove_file": "Eliminar"
 }

frontend/src/lib/components/document/BulkDocumentEditLayout.svelte.spec.ts

@@ -52,9 +52,9 @@ describe('BulkDocumentEditLayout', () => {
 			makeFile('file2.pdf')
 		]);
 
-		// Remove the chip for file1 via its "Entfernen" remove button (second × button)
+		// Remove the chip for file1 via its remove button (identified by data-remove-id)
 		const removeButtons = container.querySelectorAll<HTMLButtonElement>(
-			'[data-testid="file-switcher-strip"] button[aria-label="Entfernen"]'
+			'[data-testid="file-switcher-strip"] button[data-remove-id]'
 		);
 		expect(removeButtons.length).toBe(3);
 		removeButtons[1].click(); // remove file1

frontend/src/lib/components/document/BulkDropZone.svelte

@@ -12,7 +12,7 @@ let isDragging = $state(false);
 
 <div
 	role="region"
-	aria-label="Dateien ablegen"
+	aria-label={m.bulk_drop_zone_label()}
 	data-testid="bulk-drop-zone"
 	class="flex flex-1 flex-col items-center justify-center p-6"
 	ondragover={(e) => {
@@ -54,17 +54,13 @@ let isDragging = $state(false);
 		<p class="font-serif text-base font-bold text-ink">{m.bulk_drop_hint()}</p>
 
 		<!-- Sub description -->
-		<p class="text-sm leading-relaxed text-ink-2">
+		<p class="text-sm leading-relaxed text-ink-2">{m.bulk_drop_desc()}</p>
-			Für jede Datei wird ein eigenes Dokument erstellt.<br />
-			<strong class="text-ink">Der Titel</strong> wird aus dem Dateinamen vorausgefüllt —
-			<strong class="text-ink">alle anderen Felder</strong> gelten für alle gemeinsam.
-		</p>
 
 		<!-- CTA button -->
 		<label
 			class="flex min-h-[44px] cursor-pointer items-center rounded-sm bg-primary px-6 py-2 text-xs font-bold tracking-widest text-primary-fg uppercase transition-opacity hover:opacity-90"
 		>
-			Dateien auswählen
+			{m.bulk_select_files()}
 			<input
 				type="file"
 				multiple

frontend/src/lib/components/document/FileSwitcherStrip.svelte

@@ -58,6 +58,7 @@ $effect(() => {
 });
 </script>
 
+<div aria-live="polite" aria-atomic="true" class="sr-only"></div>
 <div
 	data-testid="file-switcher-strip"
 	class="flex h-11 shrink-0 items-center gap-1 border-t border-line bg-pdf-ctrl px-2"
@@ -71,7 +72,7 @@ $effect(() => {
 	>
 
 	<div bind:this={trackEl} class="flex flex-1 gap-1 overflow-x-auto" style="scrollbar-width:none">
-		<ul bind:this={listEl} aria-live="polite" role="list" class="flex flex-row gap-1 py-1">
+		<ul bind:this={listEl} role="list" class="flex flex-row gap-1 py-1">
 			{#each files as entry, i (entry.id)}
 				<li role="listitem" class="inline-flex shrink-0 items-center">
 					<button
@@ -102,7 +103,7 @@ $effect(() => {
 					</button>
 					<button
 						type="button"
-						aria-label="Entfernen"
+						aria-label={m.bulk_remove_file()}
 						data-remove-id={entry.id}
 						onclick={() => onRemove(entry.id)}
 						class="ml-0.5 flex h-[44px] w-[44px] items-center justify-center text-base text-ink-3 hover:text-ink focus:outline-none focus-visible:ring-2 focus-visible:ring-accent"

frontend/src/lib/components/document/FileSwitcherStrip.svelte.spec.ts

@@ -2,17 +2,10 @@ import { describe, it, expect, vi, afterEach } from 'vitest';
 import { cleanup, render } from 'vitest-browser-svelte';
 import { page, userEvent } from 'vitest/browser';
 import FileSwitcherStrip from './FileSwitcherStrip.svelte';
+import type { FileEntry } from './FileSwitcherStrip.svelte';
 
 afterEach(cleanup);
 
-export interface FileEntry {
-	id: string;
-	file: File;
-	title: string;
-	status: 'idle' | 'error';
-	previewUrl: string;
-}
-
 function makeFiles(n: number): FileEntry[] {
 	return Array.from({ length: n }, (_, i) => ({
 		id: `id-${i}`,