Implement skill self-evolution and skill_manage flow (#1874)

* chore: ignore .worktrees directory

* Add skill_manage self-evolution flow

* Fix CI regressions for skill_manage

* Address PR review feedback for skill evolution

* fix(skill-evolution): preserve history on delete

* fix(skill-evolution): tighten scanner fallbacks

* docs: add skill_manage e2e evidence screenshot

* fix(skill-manage): avoid blocking fs ops in session runtime

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/packages/harness/deerflow/config/skill_evolution_config.py

@@ -0,0 +1,14 @@
+from pydantic import BaseModel, Field
+
+
+class SkillEvolutionConfig(BaseModel):
+    """Configuration for agent-managed skill evolution."""
+
+    enabled: bool = Field(
+        default=False,
+        description="Whether the agent can create and modify skills under skills/custom.",
+    )
+    moderation_model_name: str | None = Field(
+        default=None,
+        description="Optional model name for skill security moderation. Defaults to the primary chat model.",
+    )