chore: initial baseline with P0-safety .gitignore

docs/diagrams/admin-login-sequence.mermaid

@@ -0,0 +1,16 @@
+sequenceDiagram
+    participant U as 管理员(组长)
+    participant FE as frontend-admin
+    participant API as /api/agents/login
+    participant Redis as Redis
+    participant DB as PostgreSQL
+
+    U->>FE: 输入 user_id + name 登录
+    FE->>API: POST /api/agents/login
+    API->>DB: 查询 Agent (user_id)
+    DB-->>API: Agent 记录（含 role 字段）
+    API->>Redis: 存储 token → user_id 映射
+    API-->>FE: {agent_info, token, role: "admin"}
+    FE->>FE: 检查 role === "admin"
+    FE->>FE: 存储 admin_token 到 localStorage
+    FE->>FE: 跳转到 /admin/dashboard