Limit German archive pagination to filtered results

Exclude the independent latest-release list from archived links and date boundaries. Cover stopping before the requested year, continuing within range, and rejecting pages without a filtered result block.

backend/tests/test_europe_archives.py

@@ -0,0 +1,22 @@
+from datetime import date
+from pathlib import Path
+
+import pytest
+
+from alphapulse.calendar.europe_archives import destatis_links
+
+
+@pytest.mark.parametrize("start,expected,has_next", [
+    (date(2025, 1, 1), [], False),
+    (date(2024, 1, 1), ["EN/Press/2024/09/PE24_340_611.html", "EN/Press/2024/08/PE24_329_611.html"], True),
+])
+def test_destatis_archive_only_uses_filtered_results_for_links_and_date_boundary(start, expected, has_next):
+    body = (Path(__file__).parent / "fixtures/europe/de_archive_before_start.html").read_text()
+    links, following = destatis_links(body, start, date(2026, 10, 26))
+    assert links == ["https://www.destatis.de/" + path for path in expected]
+    assert (following is not None) is has_next
+
+
+def test_destatis_archive_rejects_a_page_without_the_filtered_result_block():
+    with pytest.raises(ValueError, match="筛选结果"):
+        destatis_links("<html><body>Access denied</body></html>", date(2025, 1, 1), date(2026, 10, 26))