Implement an in-memory key-value store in Python that supports setting and retrieving values and can serialize and deserialize the entire store. Define a clear API (e.g., set(key, value), get(key), serialize(), deserialize(blob)). Choose a serialization format (e.g., JSON or pickle), explain your choice, and ensure type fidelity for common Python types (ints, floats, strings, lists, dicts). Handle missing keys and malformed or incompatible serialized input gracefully. Provide basic tests to demonstrate that data round-trips correctly.