test: use transformer and gemini-3.1-flash-lite

inference_api.py

@@ -35,7 +35,7 @@ logger = logging.getLogger("DKTInferenceEngine")
 # Global Configuration
 # ──────────────────────────────────────────────────────────────
 # Easy Switch Model Choice: 'LSTM' or 'Transformer'
-MODEL_TYPE = "LSTM"
+MODEL_TYPE = "Transformer"
 
 # Thresholds
 STRUGGLE_THRESHOLD = 0.50     # Skills below this are flagged as struggling
@@ -671,7 +671,7 @@ def trigger_gemini_explanation(skills: List[str], preference: str, question: Opt
     try:
         import google.generativeai as genai
         genai.configure(api_key=GEMINI_API_KEY)
-        model = genai.GenerativeModel("gemini-2.5-flash")
+        model = genai.GenerativeModel("gemini-3.1-flash-lite")
         response = model.generate_content(prompt)
         text = response.text.strip()
         logger.info(f"[Gemini Response]\n{text}")