fix: resolve import paths in test files and remove deprecated tests.rs

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

src/tests.rs

@@ -1,18 +1 @@
-#[cfg(test)]
-mod tests {
-    // Import the modules we need for testing
-    use crate::compression_engine::{self, CompressionType};
-    use std::str::FromStr;
-
-    mod compression_tests {
-        use super::*;
-
-        // Tests will be moved to separate files
-    }
-
-    mod compression_type_tests {
-        use super::*;
-
-        // Tests will be moved to separate files
-    }
-}
+// This file is deprecated. Tests have been moved to the modular structure in src/tests/