feat(explorer): add load_party_axis_scores helper

docs/superpowers/plans/2026-03-24-svd-tab-redesign.md

explorer.py

@@ -179,6 +179,35 @@ def load_party_map(db_path: str) -> Dict[str, str]:
         return {}
 
 
+@st.cache_data(show_spinner="Partijposities op SVD-assen laden…")
+def load_party_axis_scores(db_path: str) -> Dict[str, List[float]]:
+    """Return per-party SVD vectors for window='2025'.
+
+    Queries svd_vectors WHERE entity_type='mp' AND window_id='2025'
+    AND entity_id is a known current-parliament party.
+
+    Returns:
+        {party_name: [float * k]}  — k = 50 for the canonical 2025 window
+    """
+    try:
+        con = duckdb.connect(database=db_path, read_only=True)
+        placeholders = ", ".join("?" for _ in CURRENT_PARLIAMENT_PARTIES)
+        rows = con.execute(
+            f"SELECT entity_id, vector FROM svd_vectors "
+            f"WHERE entity_type='mp' AND window_id='2025' "
+            f"AND entity_id IN ({placeholders})",
+            list(CURRENT_PARLIAMENT_PARTIES),
+        ).fetchall()
+        con.close()
+        return {
+            row[0]: json.loads(row[1]) if isinstance(row[1], str) else list(row[1])
+            for row in rows
+        }
+    except Exception:
+        logger.exception("Failed to load party axis scores")
+        return {}
+
+
 @st.cache_data(show_spinner="Moties laden…")
 def load_motions_df(db_path: str) -> pd.DataFrame:
     """Load the full motions table as a pandas DataFrame (read-only)."""