This commit introduces store persistence and refactors the store interface for improved functionality. The changes include:
- Adding a `save` function to persist store data.
- Refactoring `createStore` to `create` and `getStore` to `get`.
- Adding `set` function to create store if not exist.
- Refactoring `set` to `hset` and `get` to `hget` for hash set and get operations.
- Refactoring `delete` to `hdel` for hash delete operations.
- Implementing store saving after each modification.
