Fix xlsx path to be relative to script location

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/streamlit_app.py

@@ -1,3 +1,4 @@
+from pathlib import Path
 import pandas as pd
 import numpy as np
 import streamlit as st
@@ -93,7 +94,7 @@ REQUIRED_COLS = {"year", "month", "site_id", "section", "model", "eqm_no", "MA",
 
 @st.cache_data
 def load_default():
-    df = pd.read_excel("bad_actor_simulation.xlsx", sheet_name="data_badactor")
+    df = pd.read_excel(Path(__file__).parent / "bad_actor_simulation.xlsx", sheet_name="data_badactor")
     df.columns = df.columns.str.strip()
     df["model"] = df["model"].astype(str)
     return df