feat(bulk-upload): add UploadSaveBar component + fix bulk_save_cta message

Save bar with sticky positioning, a determinate progress bar while
uploading chunks, plural save CTA, and a destructive discard link.
Replaces broken ICU plural in bulk_save_cta with two-key approach
(bulk_save_cta_one / bulk_save_cta) since Paraglide 2.5 does not support
ICU plural syntax.

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

frontend/messages/de.json

@@ -815,7 +815,8 @@
 	"bulk_drop_hint": "Eine oder mehrere Dateien ablegen",
 	"bulk_drop_sub": "PDF, JPEG, PNG oder TIFF · bis zu 50 MB pro Datei",
 	"bulk_count_pill": "{count} werden erstellt",
-	"bulk_save_cta": "{count, plural, one {Speichern →} other {{count} speichern →}}",
+	"bulk_save_cta_one": "Speichern →",
+	"bulk_save_cta": "{count} speichern →",
 	"bulk_discard_all": "Alle verwerfen",
 	"bulk_add_more": "Weitere hinzufügen",
 	"bulk_scope_per_file_label": "Nur diese Datei",

frontend/messages/en.json

@@ -815,7 +815,8 @@
 	"bulk_drop_hint": "Drop one or more files here",
 	"bulk_drop_sub": "PDF, JPEG, PNG or TIFF · up to 50 MB per file",
 	"bulk_count_pill": "{count} will be created",
-	"bulk_save_cta": "{count, plural, one {Save →} other {Save {count} →}}",
+	"bulk_save_cta_one": "Save →",
+	"bulk_save_cta": "Save {count} →",
 	"bulk_discard_all": "Discard all",
 	"bulk_add_more": "Add more",
 	"bulk_scope_per_file_label": "This file only",

frontend/messages/es.json

@@ -815,7 +815,8 @@
 	"bulk_drop_hint": "Suelta uno o varios archivos aquí",
 	"bulk_drop_sub": "PDF, JPEG, PNG o TIFF · hasta 50 MB por archivo",
 	"bulk_count_pill": "Se crearán {count}",
-	"bulk_save_cta": "{count, plural, one {Guardar →} other {Guardar {count} →}}",
+	"bulk_save_cta_one": "Guardar →",
+	"bulk_save_cta": "Guardar {count} →",
 	"bulk_discard_all": "Descartar todo",
 	"bulk_add_more": "Añadir más",
 	"bulk_scope_per_file_label": "Solo este archivo",

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

@@ -0,0 +1,39 @@
+<script lang="ts">
+import * as m from '$lib/paraglide/messages';
+
+let {
+	fileCount,
+	chunkProgress,
+	onSave,
+	onDiscard
+}: {
+	fileCount: number;
+	chunkProgress?: { done: number; total: number };
+	onSave: () => void;
+	onDiscard: () => void;
+} = $props();
+</script>
+
+<div
+	class="border-brand-sand sticky bottom-0 z-10 -mx-4 border-t bg-white px-6 py-4 shadow-[0_-2px_8px_rgba(0,0,0,0.06)]"
+>
+	{#if chunkProgress}
+		<progress
+			value={chunkProgress.done}
+			max={chunkProgress.total}
+			class="[&::-webkit-progress-bar]:bg-brand-sand mb-3 h-1 w-full rounded-full [&::-webkit-progress-bar]:rounded-full [&::-webkit-progress-value]:rounded-full [&::-webkit-progress-value]:bg-brand-mint"
+		></progress>
+	{/if}
+	<div class="flex items-center justify-between">
+		<button type="button" onclick={onDiscard} class="text-sm text-red-600/70 hover:text-red-700">
+			{m.bulk_discard_all()}
+		</button>
+		<button
+			type="button"
+			onclick={onSave}
+			class="min-h-[44px] rounded-sm bg-brand-navy px-6 text-sm font-bold tracking-widest text-white uppercase hover:bg-brand-navy/90"
+		>
+			{fileCount === 1 ? 'Speichern →' : `${fileCount} speichern →`}
+		</button>
+	</div>
+</div>

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

@@ -0,0 +1,48 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+import UploadSaveBar from './UploadSaveBar.svelte';
+
+afterEach(cleanup);
+
+describe('UploadSaveBar', () => {
+	it('shows plural label for multiple files', async () => {
+		render(UploadSaveBar, { fileCount: 5, onSave: vi.fn(), onDiscard: vi.fn() });
+		// "5 speichern →" or similar plural form
+		await expect.element(page.getByText(/5/)).toBeInTheDocument();
+	});
+
+	it('shows singular label for one file', async () => {
+		render(UploadSaveBar, { fileCount: 1, onSave: vi.fn(), onDiscard: vi.fn() });
+		// "Speichern →" singular form
+		await expect.element(page.getByText(/Speichern/i)).toBeInTheDocument();
+	});
+
+	it('progress bar is visible when chunkProgress is provided', async () => {
+		const { container } = render(UploadSaveBar, {
+			fileCount: 3,
+			chunkProgress: { done: 1, total: 3 },
+			onSave: vi.fn(),
+			onDiscard: vi.fn()
+		});
+		const progress = container.querySelector('progress');
+		expect(progress).not.toBeNull();
+		expect(progress?.getAttribute('value')).toBe('1');
+		expect(progress?.getAttribute('max')).toBe('3');
+	});
+
+	it('progress bar is not rendered when no chunkProgress', async () => {
+		const { container } = render(UploadSaveBar, {
+			fileCount: 2,
+			onSave: vi.fn(),
+			onDiscard: vi.fn()
+		});
+		const progress = container.querySelector('progress');
+		expect(progress).toBeNull();
+	});
+
+	it('discard link is rendered', async () => {
+		render(UploadSaveBar, { fileCount: 2, onSave: vi.fn(), onDiscard: vi.fn() });
+		await expect.element(page.getByText(/verwerfen/i)).toBeInTheDocument();
+	});
+});