fix(bulk-edit): pluralization, edit-mode CTA, error UI, real loading state

Elicit C1+C3 — bulk-selection count uses ICU-style plural keys
(bulk_edit_n_selected_one / _other) so n=1 reads as "1 Dokument" instead
of "1 Dokumente". Save CTA in edit mode reads "Anwenden" via the existing
bulk_edit_save_button key; UploadSaveBar grew an editMode prop. Multi-
chunk progress text is now visible (not aria-only).

Felix C2 — bulk-edit page wires the backend error code through
parseBackendError + getErrorMessage instead of falling back to a generic
internal_error.

Felix C5 — editAllMatching no longer swallows fetch failures: the button
shows an inline error with the backend-mapped message (e.g. when the
filter cap is exceeded).

Leonie C8 — replace the literal "…" loading glyph on /documents/bulk-edit
with a spinner + role=status + aria-live=polite + visible "Loading
documents…" text.

Leonie C9 — partial-failure card and bulk-edit page error card now use
the design-system `text-danger` / `bg-danger/10` / `border-danger/40`
tokens (dark-mode safe) instead of raw red palette values.

Leonie C10 + C13 — German plural fixed; EN badges retensed
("+ added" → "+ will be added", "replaced" → "will replace") to match
the future-tense intent of DE/ES.

Refs #225, PR #331

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

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

@@ -495,7 +495,7 @@ async function retrySave() {
 					<div
 						role="alert"
 						data-testid="bulk-edit-partial-failure"
-						class="rounded-sm border border-red-300 bg-red-50 px-4 py-3 text-sm text-red-700"
+						class="rounded-sm border border-danger/40 bg-danger/10 px-4 py-3 text-sm text-danger"
 					>
 						<p class="font-medium">
 							{m.bulk_edit_save_partial({
@@ -521,6 +521,7 @@ async function retrySave() {
 				onSave={save}
 				onDiscard={handleDiscard}
 				disabled={saving}
+				editMode={mode === 'edit'}
 			/>
 		</div>
 	</div>

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

@@ -40,7 +40,7 @@ function onEscape(e: KeyboardEvent) {
 				aria-live="polite"
 				aria-atomic="true"
 			>
-				{m.bulk_edit_n_selected({ count })}
+				{count === 1 ? m.bulk_edit_n_selected_one() : m.bulk_edit_n_selected_other({ count })}
 			</span>
 			<span class="hidden font-sans text-xs text-ink-3 sm:inline">
 				{m.bulk_edit_clear_hint_keyboard()}

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

@@ -6,14 +6,21 @@ let {
 	chunkProgress,
 	onSave,
 	onDiscard,
-	disabled = false
+	disabled = false,
+	editMode = false
 }: {
 	fileCount: number;
 	chunkProgress?: { done: number; total: number };
 	onSave: () => void;
 	onDiscard: () => void | Promise<void>;
 	disabled?: boolean;
+	editMode?: boolean;
 } = $props();
+
+const saveCta = $derived.by(() => {
+	if (editMode) return m.bulk_edit_save_button();
+	return fileCount === 1 ? m.bulk_save_cta_one() : m.bulk_save_cta({ count: fileCount });
+});
 </script>
 
 <div class="shrink-0 border-t border-line bg-surface px-4 py-3">
@@ -24,9 +31,22 @@ let {
 			aria-valuenow={chunkProgress.done}
 			aria-valuemin={0}
 			aria-valuemax={chunkProgress.total}
-			aria-label={m.bulk_upload_progress({ done: chunkProgress.done, total: chunkProgress.total })}
-			class="[&::-webkit-progress-bar]:bg-brand-sand mb-3 h-1 w-full rounded-full [&::-webkit-progress-bar]:rounded-full [&::-webkit-progress-value]:rounded-full [&::-webkit-progress-value]:bg-accent"
+			aria-label={editMode
+				? m.bulk_edit_save_progress({ done: chunkProgress.done, total: chunkProgress.total })
+				: m.bulk_upload_progress({ done: chunkProgress.done, total: chunkProgress.total })}
+			class="[&::-webkit-progress-bar]:bg-brand-sand mb-2 h-1 w-full rounded-full [&::-webkit-progress-bar]:rounded-full [&::-webkit-progress-value]:rounded-full [&::-webkit-progress-value]:bg-accent"
 		></progress>
+		{#if editMode && chunkProgress.total > 1}
+			<!-- Visible progress text for sighted users on multi-chunk PATCH
+				 (Elicit S3 — the unitless bar isn't enough for a 30-second op). -->
+			<p
+				class="mb-2 font-sans text-xs text-ink-2"
+				aria-live="polite"
+				data-testid="bulk-edit-chunk-progress-text"
+			>
+				{m.bulk_edit_save_progress({ done: chunkProgress.done, total: chunkProgress.total })}
+			</p>
+		{/if}
 	{/if}
 	<div class="flex items-center justify-between gap-3">
 		<button
@@ -43,7 +63,7 @@ let {
 			onclick={onSave}
 			class="min-h-[44px] rounded-sm bg-primary px-6 text-sm font-bold tracking-widest text-primary-fg uppercase transition-opacity hover:opacity-90 disabled:opacity-40"
 		>
-			{fileCount === 1 ? m.bulk_save_cta_one() : m.bulk_save_cta({ count: fileCount })}
+			{saveCta}
 		</button>
 	</div>
 </div>