feat: Implemented memory persistent

src/naliiabotapi/main.py

@@ -1,11 +1,43 @@
 from fastapi import FastAPI
 from naliiabotapi.api.v1.endpoints.chat import router as chat_router
 from naliiabotapi.api.v1.webhooks.chat_hook import router as chat_hook_router
+import naliiabotapi.api.dependencies as deps
+from contextlib import asynccontextmanager
+from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    deps.db_pool = deps.get_async_connection_pool()
+    await deps.db_pool.open()
+
+    async with deps.db_pool.connection() as conn:
+        checkpointer = AsyncPostgresSaver(conn)
+        await checkpointer.setup()
+
+        model_name = "anthropic"
+        naliia_prompt = deps.get_prompt_template("NALIIA_PROMPT")
+        naliia_tools = deps.NaliiaTools().get_tools()
+        config = deps.AgentConfig(system_prompt=naliia_prompt)
+        model = deps.LLMFactory(model_name).get_model()
+
+        deps.agent_instance = deps.Agent(
+            model=model,
+            config=config,
+            checkpointer=checkpointer,
+            tools=naliia_tools
+        )
+
+    yield
+
+    await deps.db_pool.close()
+
 
 app = FastAPI(
     title="NaliiaBot API",
     description="API for NaliiaBot, a chatbot that provides customer service and related topics.",
-    version="1.0.0"
+    version="1.0.0",
+    lifespan=lifespan
 )
 
 app.include_router(chat_router)