fix: import ensemble predictor at startup for ZeroGPU detection

The @spaces.GPU decorator needs to be in a module that's imported at
app startup for ZeroGPU detection to find it. Previously the module
was lazily imported inside a function, causing the detection to fail.

app.py

@@ -76,6 +76,10 @@ from backend.rate_limiting.fixed_window import TieredFixedWindowLimiter
 from backend.auth import auth, UserSession
 from backend.export import export_analysis_to_csv, export_analysis_to_pdf
 
+# Import ensemble predictor at startup so @spaces.GPU decorator is detected by ZeroGPU
+# This module contains GPU-accelerated ML forecasting (Chronos, TTM, N-HiTS)
+import backend.mcp_servers.ensemble_predictor_mcp  # noqa: F401
+
 def check_authentication(session_state: Dict) -> bool:
     """Check if user is authenticated or in demo mode."""
     if not session_state: