feat(analysis): fetch real MP metadata, fix anchor axis for party-level actors

- fetch_mp_metadata: use real OData URL with pagination (1200 records, 5 pages)
  uses Fractie.Afkorting not NaamNL for abbreviation matching
  skips Verwijderd=true records
- upsert_mp_metadata: keep most recent membership (prefer active over ended,
  then higher Van date) so current party affiliations are not overwritten by historical
- compute_anchor_axis: anchor directly on party-level SVD entities (GroenLinks-PvdA etc)
  before falling back to mp_metadata individual MP lookup
- test_fetch_mp_metadata: fix mock for timeout kwarg + pagination + Afkorting field
- Generated anchor axis HTML for 2025-Q2 through 2026-Q1 in outputs/

tests/test_fetch_mp_metadata.py

@@ -28,44 +28,58 @@ class MockResponse:
 
 
 class MockSession:
-    def __init__(self, response):
-        self._response = response
+    """Session mock that returns a data page on first call and empty page on second."""
 
-    def get(self, url):
-        return self._response
+    def __init__(self, data_page):
+        self._pages = [data_page, {"value": []}]
+        self._call = 0
+
+    def get(self, url, **kwargs):
+        resp = MockResponse(self._pages[min(self._call, len(self._pages) - 1)])
+        self._call += 1
+        return resp
 
 
 def test_fetch_mp_metadata_idempotent(tmp_path, monkeypatch):
-    # Prepare canned OData response with two FractieZetelPersoon records
+    # Prepare canned OData response with two FractieZetelPersoon records.
+    # Use Afkorting (not NaamNL) because fetch_mp_metadata prefers Afkorting.
     data = {
         "value": [
             {
+                "Verwijderd": False,
                 "Persoon": {
                     "Achternaam": "Yesilgöz-Zegerius",
                     "Initialen": "D.",
                     "Tussenvoegsel": None,
                     "Id": "guid-1",
                 },
-                "FractieZetel": {"Fractie": {"NaamNL": "VVD"}},
+                "FractieZetel": {
+                    "Fractie": {
+                        "Afkorting": "VVD",
+                        "NaamNL": "Volkspartij voor Vrijheid en Democratie",
+                    }
+                },
                 "Van": "2023-01-01",
                 "TotEnMet": None,
             },
             {
+                "Verwijderd": False,
                 "Persoon": {
                     "Achternaam": "Plas",
                     "Initialen": "C.",
                     "Tussenvoegsel": "van der",
                     "Id": "guid-2",
                 },
-                "FractieZetel": {"Fractie": {"NaamNL": "BBB"}},
+                "FractieZetel": {
+                    "Fractie": {"Afkorting": "BBB", "NaamNL": "BoerBurgerBeweging"}
+                },
                 "Van": "2023-06-01",
                 "TotEnMet": "2024-01-01",
             },
         ]
     }
 
-    mock_resp = MockResponse(data)
-    mock_session = MockSession(mock_resp)
+    mock_session = MockSession(data)
 
     # Patch requests.Session to return our mock session
     monkeypatch.setattr(requests, "Session", lambda: mock_session)
@@ -98,6 +112,7 @@ def test_fetch_mp_metadata_idempotent(tmp_path, monkeypatch):
     assert rows[1][3] == None
     assert rows[1][4] == "guid-1"
 
-    # Run again to assert idempotence (no exception and same count processed)
+    # Run again to assert idempotence: same records processed, DB unchanged
+    monkeypatch.setattr(requests, "Session", lambda: MockSession(data))
     count2 = fetch_mp_metadata(db_path=db_path, odata_url="http://example/odata")
     assert count2 == 2