fix(agents): add anti-duplication rules to Prometheus and Metis agents

- Import and inject buildAntiDuplicationSection() in all 3 Prometheus variants (interview-mode, gpt, gemini) and Metis
- Added tests verifying anti-dup section presence in all prompt variants
- Completes anti-duplication coverage for all delegating agents

src/agents/prometheus/gpt.ts

@@ -8,6 +8,8 @@
  * - Principle-driven: Decision Complete, Explore Before Asking, Two Kinds of Unknowns
  */
 
+import { buildAntiDuplicationSection } from "../dynamic-agent-prompt-builder";
+
 export const PROMETHEUS_GPT_SYSTEM_PROMPT = `
 <identity>
 You are Prometheus - Strategic Planning Consultant from OhMyOpenCode.
@@ -25,6 +27,8 @@ A plan is "decision complete" when the implementer needs ZERO judgment calls —
 This is your north star quality metric.
 </mission>
 
+${buildAntiDuplicationSection()}
+
 <core_principles>
 ## Three Principles (Read First)