feat: add AI学习助手 agent (KG+RAG ideal) and renshenguo feishu bot

- Add AI学习助手 agent creation script with all 39 tools, 3-layer KG+RAG memory
- Add renshenguo (人参果) feishu bot integration (app_service + ws_handler)
- Register renshenguo WS client in main.py startup
- Add RENSHENGUO_APP_ID / RENSHENGUO_APP_SECRET / RENSHENGUO_AGENT_ID config
- Reorganize docs from root into docs/ subdirectories
- Move startup scripts to scripts/startup/
- Various backend optimizations and tool improvements

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/tests/agent_test_cases.example.json

@@ -0,0 +1,42 @@
+{
+  "version": 1,
+  "defaults": {
+    "base_url": "http://localhost:8037",
+    "username": "admin",
+    "password": "123456",
+    "request_timeout_sec": 120,
+    "max_wait_sec": 300,
+    "poll_interval_sec": 2
+  },
+  "cases": [
+    {
+      "id": "homework-hello",
+      "name": "学生作业管理助手-打招呼",
+      "agent": { "name": "学生作业管理助手" },
+      "message": "你好",
+      "expect": {
+        "status": "completed",
+        "output_contains": ["作业", "助手"]
+      }
+    },
+    {
+      "id": "homework-by-id-smoke",
+      "name": "按 ID 冒烟（请换成你环境真实 UUID）",
+      "enabled": false,
+      "agent": { "id": "00000000-0000-0000-0000-000000000000" },
+      "message": "你好"
+    },
+    {
+      "id": "generic-with-preview-fields",
+      "name": "带预览扩展字段示例（与前端一致时可开）",
+      "enabled": false,
+      "agent": { "name": "你的Agent名称" },
+      "message": "你好",
+      "input_extra": {
+        "user_id": "preview_script_user",
+        "attachments": []
+      },
+      "expect": { "status": "completed" }
+    }
+  ]
+}