Set default model paths to load actual ML models instead of demo mode

backend/__init__.py

@@ -84,8 +84,8 @@ def create_app(config_override: dict | None = None) -> Flask:
     # ── ML model loading ─────────────────────────────────────────────────────
     from .ml.ml_engine import init_models
     init_models(
-        psycho_model_dir=os.environ.get("PSYCHO_MODEL_DIR", ""),
-        roberta_ckpt    =os.environ.get("ROBERTA_CKPT", ""),
+        psycho_model_dir=os.environ.get("PSYCHO_MODEL_DIR", "models/psychometric"),
+        roberta_ckpt    =os.environ.get("ROBERTA_CKPT", "models/text/roberta-model.pt"),
     )
 
     # ── Background scheduler ─────────────────────────────────────────────────