Add MODEL_ID env var to override GPT model selection

This change allows the GPT model to be specified via the `MODEL_ID` environment variable, enabling dynamic model selection and providing debug output for the chosen model.

app.py

@@ -356,7 +356,10 @@ def generar_analisis_fuerte(media_path):
         narrative = None
         if GPTClass:
             try:
-                wrapper = GPTClass(model="gpt-oss-120")
+                # Allow overriding model via env var MODEL_ID (e.g. "openai/gpt-oss-120b:fireworks-ai")
+                model_id = os.getenv("MODEL_ID", "gpt-oss-120")
+                print(f"DEBUG: [gpt] using model_id={model_id}, HF_USE_ROUTER={os.getenv('HF_USE_ROUTER')}")
+                wrapper = GPTClass(model=model_id)
                 # DEBUG: print prompt (truncated) so Space logs show the request
                 try:
                     print("DEBUG: [gpt] sending prompt (truncated 2000 chars):")