feat(sisyphus): add deep parallel delegation section to prompt

Add buildDeepParallelSection() function that injects guidance for non-Claude
models on parallel deep agent delegation:
- Detect when model is non-Claude and 'deep' category is available
- Inject instructions to decompose tasks and delegate to deep agents in parallel
- Give goals, not step-by-step instructions to deep agents
- Update Sisyphus prompt builder to pass model and call new function

This helps GPT-based Sisyphus instances leverage deep agents more effectively
for complex implementation tasks.

🤖 Generated with assistance of OhMyOpenCode

src/agents/dynamic-agent-prompt-builder.ts

@@ -317,6 +317,22 @@ export function buildAntiPatternsSection(): string {
 ${patterns.join("\n")}`
 }
 
+export function buildDeepParallelSection(model: string, categories: AvailableCategory[]): string {
+  const isNonClaude = !model.toLowerCase().includes('claude')
+  const hasDeepCategory = categories.some(c => c.name === 'deep')
+
+  if (!isNonClaude || !hasDeepCategory) return ""
+
+  return `### Deep Parallel Delegation
+
+For implementation tasks, actively decompose and delegate to \`deep\` category agents in parallel.
+
+1. Break the implementation into independent work units
+2. Maximize parallel deep agents — spawn one per independent unit (\`run_in_background=true\`)
+3. Give each agent a GOAL, not step-by-step instructions — deep agents explore and solve autonomously
+4. Collect results, integrate, verify coherence`
+}
+
 export function buildUltraworkSection(
   agents: AvailableAgent[],
   categories: AvailableCategory[],