feat: add argument validation for delete mode

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

src/args.rs

@@ -162,3 +162,24 @@ impl FromStr for NumberOrString {
     }
 }
 
+impl Args {
+    /// Validate the arguments based on the selected mode
+    pub fn validate(&self) -> Result<(), String> {
+        // Check if --delete is used and ids_or_tags is empty
+        if self.mode.delete && self.ids_or_tags.is_empty() {
+            return Err("At least one ID is required when using --delete".to_string());
+        }
+        
+        // Check if --delete is used and any of the ids_or_tags are tags (strings)
+        if self.mode.delete {
+            for item in &self.ids_or_tags {
+                if let NumberOrString::Str(_) = item {
+                    return Err("Tags are not supported for --delete, only IDs".to_string());
+                }
+            }
+        }
+        
+        Ok(())
+    }
+}
+