Apply suggestions from code review

Co-authored-by: Marek <mail@marek.onl>

zebra-chain/src/parameters/network.rs

@@ -65,11 +65,11 @@ impl NetworkParameters {
     }
 }
 
-#[derive(Copy, Clone, Default, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
 /// An enum describing the kind of network, whether it's the production mainnet or a testnet.
 // Note: The order of these variants is important for correct bincode (de)serialization
 //       of history trees in the db format.
 // TODO: Replace bincode (de)serialization of `HistoryTreeParts` in a db format upgrade?
+#[derive(Copy, Clone, Default, Debug, Eq, PartialEq, Hash, Serialize, Deserialize)]
 pub enum NetworkKind {
     /// The production mainnet.
     #[default]

zebra-consensus/src/parameters/subsidy.rs

@@ -231,7 +231,6 @@ impl ParameterSubsidy for Network {
             Network::Mainnet => NetworkUpgrade::Canopy
                 .activation_height(self)
                 .expect("canopy activation height should be available"),
-
             // TODO: Check what zcashd does here, consider adding a field to `NetworkParamters` to make this configurable.
             Network::Testnet(_params) => FIRST_HALVING_TESTNET,
         }

zebra-state/src/service/finalized_state/disk_format/transparent.rs

@@ -506,7 +506,8 @@ fn address_variant(address: &transparent::Address) -> u8 {
         (Mainnet, PayToPublicKeyHash { .. }) => 0,
         (Mainnet, PayToScriptHash { .. }) => 1,
         // There's no way to distinguish between Regtest and Testnet for encoded transparent addresses,
-        // so the network kind should always be `Mainnet` or `Testnet`.
+        // we can consider `Regtest` to use `Testnet` transparent addresses, so it's okay to use the `Testnet`
+        // address variant for `Regtest` transparent addresses in the db format
         (Testnet | Regtest, PayToPublicKeyHash { .. }) => 2,
         (Testnet | Regtest, PayToScriptHash { .. }) => 3,
     }