Retire unused weather bundle persistence helpers

internal/fileutil/fileutil.go

@@ -3,7 +3,6 @@ package fileutil
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -74,11 +73,3 @@ func WriteFileAtomicContext(ctx context.Context, path string, data []byte) error
 	}
 	return nil
 }
-
-func WriteJSONAtomic(path string, value any) error {
-	data, err := json.MarshalIndent(value, "", "  ")
-	if err != nil {
-		return fmt.Errorf("marshal %q: %w", path, err)
-	}
-	return WriteFileAtomic(path, data)
-}