fix: update API_URL to use environment variable for flexibility

app.py

@@ -1,4 +1,5 @@
 import io
+import os
 import subprocess
 import time
 from datetime import datetime
@@ -178,7 +179,7 @@ hr { border-color:#1e2d45 !important; }
     unsafe_allow_html=True,
 )
 
-API_URL = "http://127.0.0.1:8000/analyze"
+API_URL = os.getenv("SENTINEL_API_URL", "https://moztrk-sentinel-api.hf.space/analyze")
 
 VERDICT_COLORS = {
     "CRITICAL": "#e03030",