test(routes): cover bulk-edit-all success path + hasAdvancedFilters branches

bulk-edit-all populates the selection store on 200 response,
senderId/from/to truthy paths trigger showAdvanced.

4 new tests covering ~8 branches.

Refs #496.

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

frontend/src/routes/documents/page.svelte.test.ts

@@ -368,4 +368,48 @@ describe('documents/+ page', () => {
 			render(DocumentsListPage, { props: { data: baseData({ canWrite: true }) } })
 		).not.toThrow();
 	});
+
+	it('bulk-edit-all populates the selection store on success', async () => {
+		const fetchSpy = vi.spyOn(globalThis, 'fetch').mockResolvedValue(
+			new Response(JSON.stringify(['d-a', 'd-b', 'd-c']), {
+				status: 200,
+				headers: { 'Content-Type': 'application/json' }
+			})
+		);
+		try {
+			render(DocumentsListPage, {
+				props: { data: baseData({ canWrite: true, totalElements: 3 }) }
+			});
+
+			const btn = (await page
+				.getByRole('button', { name: /alle 3 editieren/i })
+				.element()) as HTMLButtonElement;
+			btn.click();
+
+			await new Promise((r) => setTimeout(r, 100));
+			expect(bulkSelectionStore.size).toBe(3);
+		} finally {
+			fetchSpy.mockRestore();
+		}
+	});
+
+	it('hasAdvancedFilters truthy on senderId triggers showAdvanced=true on mount', async () => {
+		expect(() =>
+			render(DocumentsListPage, {
+				props: { data: baseData({ senderId: 'p-1', initialSenderName: 'Anna' }) }
+			})
+		).not.toThrow();
+	});
+
+	it('hasAdvancedFilters truthy on from-date triggers showAdvanced=true', async () => {
+		expect(() =>
+			render(DocumentsListPage, { props: { data: baseData({ from: '1899-01-01' }) } })
+		).not.toThrow();
+	});
+
+	it('hasAdvancedFilters truthy on to-date triggers showAdvanced=true', async () => {
+		expect(() =>
+			render(DocumentsListPage, { props: { data: baseData({ to: '1950-12-31' }) } })
+		).not.toThrow();
+	});
 });