fix: replace sideways Y-axis arrows with proper top/bottom annotations

explorer.py

@@ -691,6 +691,19 @@ def _render_voting_results(voting_results_json) -> None:
 # ---------------------------------------------------------------------------
 
 
+def _add_y_direction_annotations(fig: go.Figure) -> None:
+    """Add ▲ Progressief / ▼ Conservatief labels above and below the Y axis."""
+    common = dict(
+        xref="paper",
+        yref="paper",
+        x=-0.07,
+        showarrow=False,
+        font=dict(size=11, color="#666666"),
+    )
+    fig.add_annotation(**common, y=1.02, text="▲ Progressief", xanchor="center")
+    fig.add_annotation(**common, y=-0.06, text="▼ Conservatief", xanchor="center")
+
+
 def build_compass_tab(db_path: str, window_size: str) -> None:
     st.subheader("Politiek Kompas")
     st.markdown(
@@ -809,7 +822,7 @@ def build_compass_tab(db_path: str, window_size: str) -> None:
             title=f"Politiek Kompas — {_window_label(window_idx)} (partijen)",
             labels={
                 "x": "Links ← → Rechts",
-                "y": "Progressief ↑ / Conservatief ↓",
+                "y": "Progressief / Conservatief",
                 "n": "Kamerleden",
             },
         )
@@ -827,7 +840,7 @@ def build_compass_tab(db_path: str, window_size: str) -> None:
             hover_data={"party": True, "x": ":.3f", "y": ":.3f"},
             color_discrete_map=colour_map,
             title=f"Politiek Kompas — {_window_label(window_idx)}",
-            labels={"x": "Links ← → Rechts", "y": "Progressief ↑ / Conservatief ↓"},
+            labels={"x": "Links ← → Rechts", "y": "Progressief / Conservatief"},
         )
 
     fig.update_layout(
@@ -836,6 +849,7 @@ def build_compass_tab(db_path: str, window_size: str) -> None:
         xaxis={"range": [-1, 1]},
         yaxis={"range": [-0.6, 0.6]},
     )
+    _add_y_direction_annotations(fig)
 
     with col1:
         st.plotly_chart(fig, use_container_width=True)
@@ -921,10 +935,11 @@ def build_trajectories_tab(db_path: str, window_size: str) -> None:
     fig.update_layout(
         title="Partij trajectories",
         xaxis_title="Links ← → Rechts",
-        yaxis_title="Progressief ↑ / Conservatief ↓",
+        yaxis_title="Progressief / Conservatief",
         height=600,
         legend_title_text="Partij",
     )
+    _add_y_direction_annotations(fig)
     st.plotly_chart(fig, use_container_width=True)