fix: resolve stack overflow in meta plugin initialization by removing recursive calls

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

src/meta_plugin/digest.rs

@@ -29,7 +29,7 @@ impl DigestSha256MetaPlugin {
         
         // Start with default outputs
         let mut final_outputs = std::collections::HashMap::new();
-        let default_outputs = Self::default().default_outputs();
+        let default_outputs = vec!["digest_sha256".to_string()];
         for output_name in default_outputs {
             final_outputs.insert(output_name.clone(), serde_yaml::Value::String(output_name));
         }