feat(sisyphus): enable variant='max' for maximum reasoning effort

🤖 GENERATED WITH ASSISTANCE OF [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/index.ts

@@ -255,6 +255,10 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
     },
 
     "chat.message": async (input, output) => {
+      if (input.agent === "Sisyphus") {
+        (output.message as Record<string, unknown>).variant = "max"
+      }
+
       await claudeCodeHooks["chat.message"]?.(input, output);
       await keywordDetector?.["chat.message"]?.(input, output);
       await contextInjector["chat.message"]?.(input, output);