feat(admin): surface skipped file count in ImportStatusCard

Adds SkippedFile to the local ImportStatus type and updates
ImportStatusCard to show an amber skipped-count section with a
collapsible filename list in the DONE state. Only rendered when
skipped > 0. i18n keys added for de/en/es.

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

frontend/src/routes/admin/system/ImportStatusCard.svelte.test.ts

@@ -8,6 +8,8 @@ const makeStatus = (overrides: Partial<ImportStatus> = {}): ImportStatus => ({
 	state: 'IDLE',
 	statusCode: 'IMPORT_IDLE',
 	processed: 0,
+	skipped: 0,
+	skippedFiles: [],
 	startedAt: null,
 	...overrides
 });
@@ -128,4 +130,53 @@ describe('ImportStatusCard', () => {
 		await getByRole('button').click();
 		expect(ontrigger).toHaveBeenCalledOnce();
 	});
+
+	it('shows skipped count when DONE and skipped > 0', async () => {
+		const { getByTestId } = render(ImportStatusCard, {
+			props: {
+				importStatus: makeStatus({
+					state: 'DONE',
+					statusCode: 'IMPORT_DONE',
+					processed: 10,
+					skipped: 3,
+					skippedFiles: [
+						{ filename: 'fake.pdf', reason: 'Keine gültige PDF-Signatur' },
+						{ filename: 'other.pdf', reason: 'Keine gültige PDF-Signatur' },
+						{ filename: 'tiny.pdf', reason: 'Keine gültige PDF-Signatur' }
+					]
+				}),
+				ontrigger: () => {}
+			}
+		});
+
+		await expect.element(getByTestId('skipped-count')).toHaveTextContent('3');
+	});
+
+	it('shows skipped filenames in collapsible list when DONE and skipped > 0', async () => {
+		const { getByText } = render(ImportStatusCard, {
+			props: {
+				importStatus: makeStatus({
+					state: 'DONE',
+					statusCode: 'IMPORT_DONE',
+					processed: 5,
+					skipped: 1,
+					skippedFiles: [{ filename: 'fake.pdf', reason: 'Keine gültige PDF-Signatur' }]
+				}),
+				ontrigger: () => {}
+			}
+		});
+
+		await expect.element(getByText('fake.pdf')).toBeInTheDocument();
+	});
+
+	it('does not show skipped section when DONE and skipped is 0', async () => {
+		const { getByTestId } = render(ImportStatusCard, {
+			props: {
+				importStatus: makeStatus({ state: 'DONE', statusCode: 'IMPORT_DONE', processed: 5 }),
+				ontrigger: () => {}
+			}
+		});
+
+		await expect.element(getByTestId('skipped-count')).not.toBeInTheDocument();
+	});
 });