docs: 品牌全量口径统一为「南方基金」+ 作废文档清理

1) 客服 Agent 四份交付文档 + 构建脚手架：品牌由包装占位 XX科技 / 旧名 南方财富
   统一为南方基金（热线 400-889-8899 / 官网 nffund.com），系统名改为「智能服务系统」；
   同步追加 §0.4 修订记录行，工程记录行保留原占位字面以支撑硬编码扫描验收。
2) 开发文档：清理 28 份已作废/残留文档（14 份移出归档 + 14 份仓库副本），
   新增《文档规整方案与开发前待决事项-2026-09-17》。
3) 客服agent 四份交付文档首次纳入本分支。

tests/unit/service/test_agent_factory.py

@@ -0,0 +1,36 @@
+import pytest
+
+from app.core.contracts import AgentDefinition, AgentRequest, CoreResult, RequestContext
+from app.core.errors import ValidationAgentError
+from app.service.agent.base import BaseAgent
+from app.service.agent.factory import AgentFactory
+
+
+class DemoAgent(BaseAgent):
+    async def handle(self, request: AgentRequest, context: RequestContext) -> CoreResult:
+        return CoreResult(text=request.message)
+
+
+def test_factory_creates_registered_agent() -> None:
+    definition = AgentDefinition(agent_type="demo", version="1",
+                                 allowed_roles=("customer",), allowed_portals=("api",))
+    factory = AgentFactory()
+    factory.register(definition, lambda _: DemoAgent(definition))
+    agent = factory.create("demo", RequestContext(user_id="1", trace_id="t1",
+                                                roles=("customer",), permissions=("agent:run",)))
+    assert isinstance(agent, DemoAgent)
+
+
+def test_factory_rejects_unknown_agent() -> None:
+    with pytest.raises(ValidationAgentError):
+        AgentFactory().create("unknown", RequestContext(user_id="1", trace_id="t1"))
+
+
+def test_agent_cannot_override_governance_execute() -> None:
+    with pytest.raises(TypeError):
+        class InvalidAgent(BaseAgent):
+            async def execute(self, request, context, run_id):
+                yield None
+
+            async def handle(self, request, context):
+                return CoreResult(text="invalid")