Update model name in ModelManager to use Llama-1B-Instruct for improved performance

app/services/poetry_generation.py

@@ -25,7 +25,7 @@ class ModelManager:
     
     def __init__(self):
         if not ModelManager._initialized:
-            model_name = "meta-llama/Llama-2B-Instruct"
+            model_name = "meta-llama/Llama-1B-Instruct"
             
             # Initialize tokenizer and model
             self.tokenizer = AutoTokenizer.from_pretrained(model_name)