Don't store transaction data in JSON

[Endogen]

JSON isn't optimal for storing tx data since it doesn't preserve the order of keys and after decoding and getting a dict out of it, we need to order it first.

Better to use one of the following alternatives:

1. MessagePack
   Faster than JSON for both encoding and decoding, while preserving the original structure, including key order.

Example code:

import msgpack

# Serialize data
packed_data = msgpack.packb(data_dict)

# Deserialize data
unpacked_data = msgpack.unpackb(packed_data)

2. Protocol Buffers (Protobuf)
   Is a language-neutral and platform-neutral binary serialization format. Extremely efficient and supports schema definition, which ensures data consistency and improves compatibility. Highly optimized for performance and lower payload sizes.

Protobuf requires defining a .proto schema file and generating code, so it’s a bit more setup-heavy, but given that we already use it as part of CometBFT, we should probably switch to this.