fix: replace hardcoded HF token with environment variable for security

gradio_app.py

@@ -4,6 +4,7 @@ Gradio Interface for Dynamic Forecast System
 Interactive interface for time-aware forecasting with run date selection.
 """
 
+import os
 import gradio as gr
 import polars as pl
 import pandas as pd
@@ -22,7 +23,14 @@ def load_data():
     global dataset, forecaster, borders
 
     print("[*] Loading dataset from HuggingFace...")
-    hf_token = "<HF_TOKEN>"
+
+    # Load HF token from environment variable
+    hf_token = os.getenv("HF_TOKEN")
+    if not hf_token:
+        raise ValueError(
+            "HF_TOKEN not found in environment variables. "
+            "Please set HF_TOKEN in your environment or .env file."
+        )
 
     ds = load_dataset(
         "evgueni-p/fbmc-features-24month",