Fix dashboard imports for Streamlit multi-page routing

- Add sys.path.insert at top of app.py and all 5 page files
- Fix .streamlit/config.toml CORS/XSRF conflict
- Remove duplicate st.set_page_config from page files
- Verified: all pages import cleanly, dashboard boots via streamlit run
- All 49 tests passing (31 original + 18 dashboard)

dashboard/pages/01_matchday.py

@@ -1,3 +1,4 @@
+import sys; from pathlib import Path; _p = Path(__file__).resolve().parent.parent.parent; str(_p) not in sys.path and sys.path.insert(0, str(_p))
 """Page 1 — Matchday Control Room.
 
 KPI row, fixture difficulty heatmap, start/sit table, bump chart.
@@ -59,7 +60,6 @@ def _build_fixture_heatmap(players, fixtures):
 
 
 def run():
-    st.set_page_config(page_title="Matchday — Fantabeto", page_icon="⚽", layout="wide")
     inject_css()
     preds, fixtures, players, lineups, votes = _get_data()