Add scoped Agent-mode pipeline as experimental Classic fork.

Wire specialist waves, Brain consolidation, and Classic-compatible reports so Agent mode can run end-to-end via OpenRouter without changing the default Classic path.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/pipeline/runner.py

@@ -147,6 +147,7 @@ def run_pipeline(
     report["summary"]["cost_by_stage"] = cost.get("by_stage", {})
     report["summary"]["text_backend"] = "local" if text_local else "openrouter"
     report["summary"]["models_used"] = cost.get("models", {})
+    report["summary"]["pipeline_mode"] = "classic"
     print(f"[Runner] LLM cost: ${cost['usd']:.4f} over {cost['calls']} live calls"
           f" ({cost.get('cached', 0)} cached)")