apply Emily's suggestions

* add `PMaxTimeRangeWidth`
* several `Default` instances for testing
* a bunch of docstrings
* fix the tests/samples

agora/Agora/Governor.hs

@@ -37,13 +37,17 @@ import Agora.Proposal (
   ProposalId (ProposalId),
   ProposalThresholds,
  )
-import Agora.Proposal.Time (PProposalTimingConfig, ProposalTimingConfig)
+import Agora.Proposal.Time (
+  MaxTimeRangeWidth,
+  PMaxTimeRangeWidth,
+  PProposalTimingConfig,
+  ProposalTimingConfig,
+ )
 import Agora.SafeMoney (GTTag)
 import Agora.Utils (tclet)
 
 --------------------------------------------------------------------------------
 
-import Plutarch.Api.V1 (PPOSIXTime)
 import Plutarch.DataRepr (
   DerivePConstantViaData (..),
   PDataFields,
@@ -56,7 +60,7 @@ import Plutarch.Unsafe (punsafeCoerce)
 
 --------------------------------------------------------------------------------
 
-import Plutus.V1.Ledger.Api (POSIXTime, TxOutRef)
+import Plutus.V1.Ledger.Api (TxOutRef)
 import Plutus.V1.Ledger.Value (AssetClass (..))
 import PlutusTx qualified
 
@@ -71,7 +75,7 @@ data GovernorDatum = GovernorDatum
   , proposalTimings :: ProposalTimingConfig
   -- ^ The timing configuration for proposals.
   --   Will get copied over upon the creation of proposals.
-  , createProposalTimeRangeMaxDuration :: POSIXTime
+  , createProposalTimeRangeMaxWidth :: MaxTimeRangeWidth
   -- ^ The maximum valid duration of a transaction that creats a proposal.
   }
   deriving stock (Show, GHC.Generic)
@@ -126,7 +130,7 @@ newtype PGovernorDatum (s :: S) = PGovernorDatum
           '[ "proposalThresholds" ':= PProposalThresholds
            , "nextProposalId" ':= PProposalId
            , "proposalTimings" ':= PProposalTimingConfig
-           , "createProposalTimeRangeMaxDuration" ':= PPOSIXTime
+           , "createProposalTimeRangeMaxWidth" ':= PMaxTimeRangeWidth
            ]
       )
   }