support prompt template loading

src/text_generation/adapters/prompt_template_repository.py

@@ -0,0 +1,19 @@
+import os
+from src.text_generation.ports.abstract_prompt_template_repository import AbstractPromptTemplateRepository
+from langchain_core.prompts import load_prompt, PromptTemplate
+
+
+class PromptTemplateRepository(AbstractPromptTemplateRepository):
+    def __init__(self):
+        super().__init__()
+        self.templates_dir = os.environ.get('PROMPT_TEMPLATES_DIR')
+    
+    def _create_path_from_id(self, id: str) -> str:
+        template_filename = f'{id}.json'
+        return os.path.join(self.templates_dir, template_filename)
+
+    def get(self, id: str) -> PromptTemplate:
+        return load_prompt(self._create_path_from_id(id))
+    
+    def add(self, id: str, prompt_template: PromptTemplate) -> None:
+        prompt_template.save(self._create_path_from_id(id))