gzipEncode function
Stub gzip implementation for platforms without dart:io (e.g., web).
Returns null since gzip is unavailable on these platforms.
Gzip-encodes bytes. Returns null on unsupported platforms.
Implementation
/// Gzip-encodes [bytes]. Returns `null` on unsupported platforms.
List<int>? gzipEncode(List<int> bytes) => null;