feat: auto-forward single-subcommand groups

When a group has exactly one leaf command, typing the group name
alone executes it directly instead of erroring.

  minimax quota  →  minimax quota show
  minimax music  →  minimax music generate
  minimax search →  minimax search query

Groups with multiple subcommands (auth, video, text, etc.) are
unaffected and still show the group help.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: RyanLee-Dev

src/registry.ts

@@ -77,6 +77,14 @@ class CommandRegistry {
       return { command: node.command, extra: commandPath.slice(matched.length) };
     }
 
+    // Single child: auto-forward (e.g. `minimax quota` → `minimax quota show`)
+    if (matched.length > 0 && node.children.size === 1) {
+      const [, child] = node.children.entries().next().value as [string, CommandNode];
+      if (child.command) {
+        return { command: child.command, extra: commandPath.slice(matched.length) };
+      }
+    }
+
     // If we matched some path but no command, show help for that group
     if (matched.length > 0 && node.children.size > 0) {
       const subcommands = Array.from(node.children.entries())