feat: Live-Stempel-Uhr, Break-UI, Balance-Widget, Approval-Queue + PDF-Export (WeasyPrint)

Frontend (TimeTrackingPage):
- Live-Arbeitsuhr (HH:MM:SS) während eingestempelt
- Break-Start/End-Buttons mit laufender Pausenuhr
- Wochen-Balance-Widget (gearbeitet / erwartet / überstunden)
- Approval-Queue Tab für Manager/HR/Admin (pending entries genehmigen/ablehnen)

Backend (Reports):
- weasyprint>=61.0 in requirements.txt
- 3 neue PDF-Export-Tests (Zeit, Abwesenheit, Überstunden)

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

backend/tests/test_reports.py

@@ -308,3 +308,47 @@ def test_to_xlsx_with_data():
     result = svc.to_xlsx(rows, sheet_name="Test")
     assert isinstance(result, bytes)
     assert len(result) > 1000  # XLSX ist ZIP-basiert
+
+
+# ── PDF Export ─────────────────────────────────────────────────────────────────
+
+@pytest.mark.asyncio
+async def test_export_time_pdf(client: AsyncClient, report_headers):
+    today = date.today()
+    resp = await client.get(
+        "/api/v1/reports/time/export",
+        params={"date_from": str(today.replace(day=1)), "date_to": str(today), "format": "pdf"},
+        headers=report_headers,
+    )
+    assert resp.status_code == 200
+    assert "pdf" in resp.headers["content-type"]
+    assert "attachment" in resp.headers.get("content-disposition", "")
+    assert len(resp.content) > 1000
+
+
+@pytest.mark.asyncio
+async def test_export_absence_pdf(client: AsyncClient, report_headers):
+    today = date.today()
+    resp = await client.get(
+        "/api/v1/reports/absences/export",
+        params={"date_from": str(today.replace(day=1)), "date_to": str(today), "format": "pdf"},
+        headers=report_headers,
+    )
+    assert resp.status_code == 200
+    assert "pdf" in resp.headers["content-type"]
+    assert "attachment" in resp.headers.get("content-disposition", "")
+    assert len(resp.content) > 1000
+
+
+@pytest.mark.asyncio
+async def test_export_overtime_pdf(client: AsyncClient, report_headers):
+    today = date.today()
+    resp = await client.get(
+        "/api/v1/reports/overtime/export",
+        params={"date_from": str(today.replace(day=1)), "date_to": str(today), "format": "pdf"},
+        headers=report_headers,
+    )
+    assert resp.status_code == 200
+    assert "pdf" in resp.headers["content-type"]
+    assert "attachment" in resp.headers.get("content-disposition", "")
+    assert len(resp.content) > 1000