feat: add default_options method to all meta plugins

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

src/meta_plugin/program.rs

@@ -163,4 +163,8 @@ impl MetaPlugin for MetaPluginProgram {
     fn default_outputs(&self) -> Vec<String> {
         vec![self.meta_name.clone()]
     }
+    
+    fn default_options(&self) -> std::collections::HashMap<String, serde_yaml::Value> {
+        std::collections::HashMap::new()
+    }
 }