feat: 可配置方案引擎通用原型（Mock 检索）

需求未定稿时可先跑通追问/判定/出方案；槽位与判定树外置 YAML，后续可接 Ragflow。

Co-authored-by: haijd <haijd@163.com>

engine/app/config_loader.py

@@ -0,0 +1,53 @@
+from __future__ import annotations
+
+from typing import Any
+
+import yaml
+
+from .settings import settings
+
+
+def _load_yaml(name: str) -> dict[str, Any]:
+    path = settings.knowledge_dir / name
+    with path.open(encoding="utf-8") as f:
+        data = yaml.safe_load(f) or {}
+    if not isinstance(data, dict):
+        raise ValueError(f"{name} must be a mapping")
+    return data
+
+
+class BusinessConfig:
+    def __init__(self) -> None:
+        self.reload()
+
+    def reload(self) -> None:
+        self.slots_doc = _load_yaml("slots.yaml")
+        self.tree_doc = _load_yaml("decision_tree.yaml")
+        self.chunks_doc = _load_yaml("sample_chunks.yaml")
+
+    @property
+    def slots(self) -> list[dict[str, Any]]:
+        return list(self.slots_doc.get("slots") or [])
+
+    @property
+    def handoff_phrases(self) -> list[str]:
+        return list(self.slots_doc.get("handoff_phrases") or [])
+
+    @property
+    def closing_prompt(self) -> str:
+        return str(self.slots_doc.get("closing_prompt") or "正在生成方案…")
+
+    @property
+    def rules(self) -> list[dict[str, Any]]:
+        return sorted(self.tree_doc.get("rules") or [], key=lambda r: r.get("order", 100))
+
+    @property
+    def handoff_confidence_below(self) -> float:
+        return float(self.tree_doc.get("handoff_confidence_below", 0.55))
+
+    @property
+    def chunks(self) -> list[dict[str, Any]]:
+        return list(self.chunks_doc.get("chunks") or [])
+
+
+business_config = BusinessConfig()