refactor: split compression tests into separate module files as planned

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/tests/compression/mod.rs

@@ -0,0 +1,17 @@
+#[cfg(test)]
+pub mod gzip_tests;
+#[cfg(test)]
+pub mod lz4_tests;
+#[cfg(test)]
+pub mod none_tests;
+
+#[cfg(test)]
+mod tests {
+    use tempfile::tempdir;
+    use std::io::Write;
+    
+    // Import the modules we need for testing
+    use crate::compression_engine::gzip::CompressionEngineGZip;
+    use crate::compression_engine::lz4::CompressionEngineLZ4;
+    use crate::compression_engine::none::CompressionEngineNone;
+}