fix: omit skills section in minimal prompt

src/agents/system-prompt.ts

@@ -17,6 +17,7 @@ function buildSkillsSection(params: {
   isMinimal: boolean;
   readToolName: string;
 }) {
+  if (params.isMinimal) return [];
   const trimmed = params.skillsPrompt?.trim();
   if (!trimmed) return [];
   return [