feat: Implement registry for meta plugins

Co-authored-by: aider (openai/andrew/openrouter/deepseek/deepseek-chat-v3.1) <aider@aider.chat>

src/meta_plugin/env.rs

@@ -138,3 +138,13 @@ impl MetaPlugin for EnvMetaPlugin {
         panic!("options_mut() not implemented for EnvMetaPlugin")
     }
 }
+use crate::meta_plugin::register_meta_plugin;
+use crate::meta_plugin::MetaPluginType;
+
+// Register the plugin at module initialization time
+#[ctor::ctor]
+fn register_env_plugin() {
+    register_meta_plugin(MetaPluginType::Env, |options, outputs| {
+        Box::new(EnvMetaPlugin::new(options, outputs))
+    });
+}