feat(skill-learning): add surrogate tool evaluator

app-instance/backend/beaver/skills/learning/__init__.py

@@ -13,6 +13,7 @@ from .pipeline import SkillLearningPipelineService
 from .preservation import check_preservation
 from .replay import ReplayToolExecutor, ReplayToolPolicy, classify_tool_mode
 from .service import RunReceiptContext, SkillLearningService
+from .surrogate import SurrogateToolEvaluator
 from .synthesizer import SkillDraftSynthesizer
 from .worker import SkillLearningWorker, SkillLearningWorkerConfig, SkillLearningWorkerResult
 
@@ -31,6 +32,7 @@ __all__ = [
     "ReplayToolExecutor",
     "ReplayToolPolicy",
     "classify_tool_mode",
+    "SurrogateToolEvaluator",
     "SkillDraftSynthesizer",
     "SkillLearningService",
     "SkillLearningWorker",