refactor: Isolate conditional compilation of magic_file plugin import

Co-authored-by: aider (openai/andrew/openrouter/sonoma-sky-alpha) <aider@aider.chat>

src/lib.rs

@@ -29,12 +29,14 @@ use filter_plugin::{
 // Import all meta plugins to ensure they register themselves
 #[allow(unused_imports)]
 use meta_plugin::{
-    #[cfg(feature = "magic")]
-    magic_file,
     cwd, text, user, shell, shell_pid, keep_pid, digest, 
     read_time, read_rate, hostname, exec, env
 };
 
+#[cfg(feature = "magic")]
+#[allow(unused_imports)]
+use meta_plugin::magic_file;
+
 // Initialize plugins at library load time
 pub fn init_plugins() {
     // This will be expanded in Step 3 implementation