Code cleanup and deduplication pass through weatherfeeder

internal/normalizers/builtins.go

@@ -9,6 +9,12 @@ import (
 	"gitea.maximumdirect.net/ejr/weatherfeeder/internal/normalizers/openweather"
 )
 
+var builtinRegistrations = []func([]fknormalize.Normalizer) []fknormalize.Normalizer{
+	nws.Register,
+	openmeteo.Register,
+	openweather.Register,
+}
+
 // RegisterBuiltins registers all normalizers shipped with this binary.
 //
 // This mirrors internal/sources.RegisterBuiltins, but note the selection model:
@@ -27,9 +33,9 @@ func RegisterBuiltins(in []fknormalize.Normalizer) []fknormalize.Normalizer {
 	//
 	// Order here should be stable across releases to reduce surprises when adding
 	// new normalizers.
-	out = nws.Register(out)
-	out = openmeteo.Register(out)
-	out = openweather.Register(out)
+	for _, register := range builtinRegistrations {
+		out = register(out)
+	}
 
 	return out
 }