fix: remove unused delete_item handler and add accessors for unused fields

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

src/args.rs

@@ -190,3 +190,13 @@ impl FromStr for KeyValue {
         }
     }
 }
+
+impl KeyValue {
+    pub fn key(&self) -> &str {
+        &self.key
+    }
+    
+    pub fn value(&self) -> &str {
+        &self.value
+    }
+}