feat(minimax): add /usage support and fix MiniMax quota parsing (#869)

* Add MiniMax usage UI and API support

* Fix MiniMax usage parsing and refresh UI

* Refactor MiniMax usage handling

src/commands/usage/index.ts

@@ -4,6 +4,5 @@ export default {
   type: 'local-jsx',
   name: 'usage',
   description: 'Show plan usage limits',
-  availability: ['claude-ai'],
   load: () => import('./usage.js'),
 } satisfies Command