feat: warn when meta plugins are enabled but not supported

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

src/modes/save.rs

@@ -68,6 +68,13 @@ pub fn mode_save(
         .map(|meta_plugin_type| get_meta_plugin(meta_plugin_type))
         .collect();
     
+    // Check for unsupported meta plugins and warn the user
+    for (meta_plugin, meta_plugin_type) in meta_plugins.iter().zip(&meta_plugin_types) {
+        if !meta_plugin.is_supported() {
+            eprintln!("Warning: Meta plugin '{}' is enabled but not supported on this system", meta_plugin_type);
+        }
+    }
+
     let mut item = db::Item {
         id: None,
         ts: Utc::now(),