Refactor code structure for improved readability and maintainability

app/main.py

@@ -0,0 +1,26 @@
+from collections.abc import AsyncGenerator
+from contextlib import asynccontextmanager
+
+from fastapi import FastAPI
+
+from app.core.database import init_db
+
+
+@asynccontextmanager
+async def lifespan(_app: FastAPI) -> AsyncGenerator[None, None]:
+
+    await init_db()
+    yield
+
+
+def create_app() -> FastAPI:
+    app = FastAPI(lifespan=lifespan)
+
+    @app.get("/")
+    def health() -> dict[str, str]:
+        return {"status": "healthy"}
+
+    return app
+
+
+app = create_app()