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/decision.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from typing import Any
+
+
+def _match_condition(cond: dict[str, Any], slots: dict[str, str]) -> bool:
+    ctype = cond.get("type")
+    if ctype == "always":
+        return True
+    slot = str(cond.get("slot") or "")
+    value = str(cond.get("value") or "")
+    actual = (slots.get(slot) or "").strip()
+    if ctype == "slot_equals":
+        return actual == value
+    if ctype == "slot_contains":
+        return value.lower() in actual.lower()
+    return False
+
+
+def evaluate_tree(rules: list[dict[str, Any]], slots: dict[str, str]) -> dict[str, Any]:
+    for rule in rules:
+        conditions = rule.get("when_all") or []
+        if all(_match_condition(c, slots) for c in conditions):
+            then = dict(rule.get("then") or {})
+            return {
+                "rule_id": rule.get("id"),
+                "description": rule.get("description"),
+                **then,
+            }
+    return {
+        "rule_id": "empty",
+        "product_bundle": ["待专家确认"],
+        "tech_line": "待判定",
+        "summary": "未匹配到规则",
+        "confidence": 0.0,
+        "handoff": True,
+    }