feat(ocr): add PREPROCESSING_PAGE progress translation and i18n strings

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

frontend/src/lib/ocr/translateOcrProgress.spec.ts

@@ -12,6 +12,8 @@ vi.mock('$lib/paraglide/messages.js', () => ({
 			`${count} Blöcke erstellt, ${skipped} Seite(n) übersprungen`,
 		ocr_status_analyzing_page: ({ current, total }: { current: string; total: string }) =>
 			`Seite ${current} von ${total} wird analysiert…`,
+		ocr_status_preprocessing_page: ({ current, total }: { current: string; total: string }) =>
+			`Seite ${current} von ${total} wird aufbereitet…`,
 		ocr_status_error: () => 'OCR fehlgeschlagen'
 	}
 }));
@@ -68,6 +70,13 @@ describe('translateOcrProgress', () => {
 		expect(result.totalPages).toBe(5);
 	});
 
+	it('translates PREPROCESSING_PAGE with current and total', () => {
+		const result = translateOcrProgress('PREPROCESSING_PAGE:3:10');
+		expect(result.message).toBe('Seite 3 von 10 wird aufbereitet…');
+		expect(result.currentPage).toBe(3);
+		expect(result.totalPages).toBe(10);
+	});
+
 	it('translates ERROR', () => {
 		expect(translateOcrProgress('ERROR').message).toBe('OCR fehlgeschlagen');
 	});

frontend/src/lib/ocr/translateOcrProgress.ts

@@ -48,6 +48,18 @@ export function translateOcrProgress(code: string): OcrProgressResult {
 				totalPages: total
 			};
 		}
+		case 'PREPROCESSING_PAGE': {
+			const current = parseInt(parts[1] ?? '0', 10);
+			const total = parseInt(parts[2] ?? '0', 10);
+			return {
+				message: m.ocr_status_preprocessing_page({
+					current: String(current),
+					total: String(total)
+				}),
+				currentPage: current,
+				totalPages: total
+			};
+		}
 		case 'ERROR':
 			return { message: m.ocr_status_error() };
 		default: