refactor: tests目录精简重构 + 脏数据清理脚本

- 删除16个旧Python测试文件(970行→400行)
- 重写conftest.py适配真实种子用户(admin/test123/test234/testtest/logan)
- 5个精简测试文件覆盖核心API:
  - test_auth.py: 登录/鉴权/种子用户验证 (6 tests)
  - test_instances.py: 实例列表/详情/连接测试 (6 tests)
  - test_tickets.py: 工单CRUD/只读SQL拦截/auditor权限 (7 tests)
  - test_workflow.py: E2E完整审批流/拒绝/撤销 (3 tests)
  - test_permissions.py: 角色权限/执行权限/workflow权限 (6 tests)
- 新增 cleanup_test_data.py 清理测试脏数据(支持--dry-run)
- 全量29测试3.27s通过

tests/test_auth.py

@@ -1,39 +1,51 @@
-"""Auth endpoint tests — Go/Gin backend."""
+"""Auth API tests"""
 import pytest
 from httpx import AsyncClient
-from tests.conftest import auth_header
+def auth_header(token: str) -> dict:
+    return {"Authorization": f"Bearer {token}"}
 
 
 class TestLogin:
     async def test_admin_login(self, client: AsyncClient):
         resp = await client.post("/api/v1/auth/login", json={
-            "username": "admin", "password": "admin123"
+            "username": "admin", "password": "admin123",
         })
         assert resp.status_code == 200
-        data = resp.json()
-        assert "access_token" in data
+        assert "access_token" in resp.json()
+
+    async def test_all_seed_users_login(self, client: AsyncClient):
+        """验证所有种子用户都能登录"""
+        users = {
+            "admin": "admin123", "test123": "test123",
+            "test234": "test234", "testtest": "testtest", "logan": "zxc987",
+        }
+        for username, password in users.items():
+            resp = await client.post("/api/v1/auth/login", json={
+                "username": username, "password": password,
+            })
+            assert resp.status_code == 200, f"{username} login failed"
+            assert "access_token" in resp.json()
 
     async def test_wrong_password(self, client: AsyncClient):
         resp = await client.post("/api/v1/auth/login", json={
-            "username": "admin", "password": "wrong"
+            "username": "admin", "password": "wrong",
         })
         assert resp.status_code == 401
 
     async def test_nonexistent_user(self, client: AsyncClient):
         resp = await client.post("/api/v1/auth/login", json={
-            "username": "nobody", "password": "test"
+            "username": "nobody", "password": "xxx",
         })
         assert resp.status_code == 401
 
 
 class TestGetMe:
-    async def test_get_me(self, client: AsyncClient, admin_token: str):
+    async def test_get_me(self, client: AsyncClient, admin_token):
         resp = await client.get("/api/v1/auth/me", headers=auth_header(admin_token))
         assert resp.status_code == 200
         data = resp.json()
         assert data["username"] == "admin"
-        assert "role" in data
-        assert "id" in data
+        assert data["role"] == "admin"
 
     async def test_no_token(self, client: AsyncClient):
         resp = await client.get("/api/v1/auth/me")