feat: 添加可配置场景注册表与规则引擎

- 新增场景基类、配置加载、注册表与原语模块
- 添加 r10_refund_split 规则及场景 JSON Schema
- 扩展 scan 引擎与 scenarios API
- 新增场景注册表/配置/集成测试
- 更新前端 App、api、labels 支持新场景

backend/app/scenarios/rules/scenario.schema.json

@@ -0,0 +1,53 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "AIAudit 配置驱动场景",
+  "description": "配置驱动审计场景（B 快捷通道）的 schema，对应 app.scenarios.config.ScenarioConfig；权威校验以后端 pydantic 为准。",
+  "type": "object",
+  "required": ["code", "title", "risk_domain", "label", "detector"],
+  "additionalProperties": false,
+  "properties": {
+    "code": {
+      "type": "string",
+      "minLength": 1,
+      "description": "场景码，全局唯一，如 R10"
+    },
+    "title": {
+      "type": "string",
+      "minLength": 1,
+      "description": "默认线索标题"
+    },
+    "risk_domain": {
+      "type": "string",
+      "minLength": 1,
+      "description": "风险域，如 收入/成本"
+    },
+    "label": {
+      "type": "string",
+      "minLength": 1,
+      "description": "前端展示名"
+    },
+    "detector": {
+      "type": "string",
+      "minLength": 1,
+      "description": "检测原语名（见 app/scenarios/primitives.py）",
+      "examples": ["threshold_edge", "cliff_drop", "ratio_threshold"]
+    },
+    "params": {
+      "type": "object",
+      "description": "传给检测原语的参数（键随原语而定）"
+    },
+    "threshold": {
+      "type": "number",
+      "description": "评分阈值：草稿 score >= 阈值才生成线索",
+      "default": 0.5
+    },
+    "rationale_template": {
+      "type": "string",
+      "description": "线索理由模板，支持 {summary} 及原语 metrics 中的占位符"
+    },
+    "rule_version": {
+      "type": ["string", "null"],
+      "description": "规则版本，用于线索可追溯"
+    }
+  }
+}