fix: enable and fix all existing tests by updating module imports and test implementations

Co-authored-by: aider (openai/andrew/openrouter/anthropic/claude-sonnet-4) <aider@aider.chat>

src/lib.rs

@@ -11,9 +11,4 @@ pub mod args;
 pub use args::Args;
 
 #[cfg(test)]
-mod tests {
-    #[test]
-    fn test_library_structure() {
-        assert!(true);
-    }
-}
+mod tests;