feat(phase6): implement end-to-end enterprise scenario validation (U15)
- Add goal-driven agent skill config and pipeline config
- Add 9 E2E integration tests covering all 7 capabilities:
- SC1: Goal-driven SEO analysis (GoalPlanner→PlanExecutor→PlanChecker→ExperienceStore)
- SC2: Knowledge Q&A with system operation (MultiSourceRAG)
- SC3: Workflow with approval (WorkflowStore + approval node)
- SC4: Self-evolution experience accumulation (ExperienceStore→PitfallDetector→PathOptimizer)
- SC5: Parallel execution efficiency verification
- SC6: Skill registry integration (capabilities, versions, health)
- Cross-capability: Plan+Experience+Pitfall, Review+Experience, RAG+Workflow
- All 2472 tests passing (9 integration + 2463 unit)
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