Store historical protocol parameters by epoch in parameters_state

[whankinsiv]

Currently parameters_state only stores the current protocol parameters. This limits our ability to inspect or query historical protocol parameters for observability, debugging, and analytical needs. This issue proposes updating parameters_state to store protocol parameters in a BTreeMap<Epoch, ProtocolParameters> where:

• The key is the epoch when the parameters were enacted.
• The value is the protocol parameters themselves.

This design would allow us to:

• Query historical protocol parameters efficiently.
• Assume that any epoch between two entries uses the parameters stored in the prior entry.
• Improve transparency of protocol state transitions over time.

[sandtreader]

Note the history tree will need to handle rollbacks over an epoch boundary