test: annotate runtime:Channel.message for the VM parity coverage gate

Adding Channel.message as a runtime intrinsic (for cross-isolate message channels)
introduced a new supported VM feature; parity_fixture_annotations_cover_supported_vm_features
requires a `// parity:` annotation for it. Channel.message reuses the Channel.bounded
runtime path and is parity-tested by parity_message_channel_roundtrip, so add it to
the Channel annotation line.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: olwang

crates/rsscript/tests/vm_eval.rs

@@ -800,7 +800,7 @@ pub fn echo(message: &String) -> String {
 // parity: runtime:Buffer.new runtime:Buffer.view runtime:BufferView.is_empty
 // parity: runtime:BufferView.len runtime:BufferView.slice runtime:BufferView.to_bytes
 // parity: runtime:Cache.get runtime:Cache.insert runtime:Cache.lookup runtime:Cache.new
-// parity: runtime:Channel.bounded runtime:Channel.receiver runtime:Channel.sender
+// parity: runtime:Channel.bounded runtime:Channel.message runtime:Channel.receiver runtime:Channel.sender
 // parity: runtime:ChannelError.message
 // parity: runtime:CancellationSource.cancel runtime:CancellationSource.new
 // parity: runtime:CancellationSource.token runtime:CancellationToken.is_cancelled