feat(healthcheck): enhance health check functionality and serve favicon directly

healthcheck.py

@@ -5,10 +5,11 @@ import os
 
 def check_health():
     try:
-        host = os.environ.get('ADGUARD_HOST', 'http://localhost')
+        host = os.environ.get('ADGUARD_HOST', 'localhost')
         port = os.environ.get('ADGUARD_PORT', '8000')
+        url = f'http://{host}:{port}/health'
         with httpx.Client() as client:
-            response = client.get('http://localhost:8000/health')
+            response = client.get(url)
             response.raise_for_status()
         print('✅ Service is healthy')
         sys.exit(0)