agent: drop unused FromField SimplexNameInfo

The instance landed in the previous commit alongside ToField but has
zero consumers in either repo — chat-side row decoders use the
soft-degradation `decodeSimplexName` helper at the tuple level, never
this instance. `fromTextField_` raises ConversionFailed on parse
failure, which doesn't compose with the chat policy.

Keep ToField (used by parameter binding in name lookups). Leave a
comment explaining why FromField is absent so a future contributor
doesn't reintroduce it without thinking about the decode policy.

Author: shumvgolove

src/Simplex/Messaging/SimplexName.hs

@@ -28,10 +28,10 @@ import Data.Functor (($>))
 import Data.Text (Text)
 import qualified Data.Text as T
 import Data.Text.Encoding (decodeLatin1, encodeUtf8)
-import Simplex.Messaging.Agent.Store.DB (FromField (..), ToField (..), fromTextField_)
+import Simplex.Messaging.Agent.Store.DB (ToField (..))
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Parsers (defaultJSON, dropPrefix, enumJSON)
-import Simplex.Messaging.Util (eitherToMaybe, safeDecodeUtf8, (<$?>))
+import Simplex.Messaging.Util (safeDecodeUtf8, (<$?>))
 
 data SimplexNameInfo = SimplexNameInfo
   { nameType :: SimplexNameType,
@@ -124,10 +124,13 @@ shortNameInfoStr = \case
         NTPublicGroup -> "#"
         NTContact -> "@"
 
+-- | Stored as TEXT. The matching `FromField` instance is intentionally not
+-- defined: existing consumers want soft-decode semantics (parse failure
+-- degrades to `Nothing` rather than failing the row), which doesn't
+-- compose with `fromTextField_`. Add a `FromField` instance here only
+-- when a consumer wants the row-fail behaviour and document the divide.
 instance ToField SimplexNameInfo where toField = toField . decodeLatin1 . strEncode
 
-instance FromField SimplexNameInfo where fromField = fromTextField_ $ eitherToMaybe . strDecode . encodeUtf8
-
 $(J.deriveJSON (enumJSON $ dropPrefix "TLD") ''SimplexTLD)
 
 $(J.deriveJSON (enumJSON $ dropPrefix "NT") ''SimplexNameType)