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/cleanup_test_data.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env python3
+"""
+Cleanup test data from SQLite database.
+Removes tickets, approvals, and test-created tables, preserving seed data.
+
+Usage:
+    python tests/cleanup_test_data.py          # full cleanup
+    python tests/cleanup_test_data.py --dry-run # preview only
+"""
+import sqlite3
+import sys
+import os
+
+DB_PATH = os.path.join(os.path.dirname(__file__), '..', 'backend', 'sqlite3.db')
+
+# Tables in remote MySQL that were created by tests (DROP IF EXISTS)
+TEST_MYSQL_TABLES = [
+    "_test_tbl", "_e2e_test", "_reject_test", "_cancel_test", "_perm_test",
+    "orders", "_ghost_test_del", "flow_test", "ghost_test",
+]
+
+
+def cleanup(dry_run=False):
+    db = sqlite3.connect(DB_PATH)
+    cur = db.cursor()
+
+    actions = []
+
+    # 1. Count and delete ticket-related data
+    for table in ["ticket_sql_items", "ticket_approvals", "tickets"]:
+        cur.execute(f"SELECT COUNT(*) FROM {table}")
+        count = cur.fetchone()[0]
+        if count > 0:
+            actions.append(f"DELETE {count} rows FROM {table}")
+            if not dry_run:
+                cur.execute(f"DELETE FROM {table}")
+
+    # 2. Count query history
+    cur.execute("SELECT name FROM sqlite_master WHERE type='table' AND name='query_history'")
+    if cur.fetchone():
+        cur.execute("SELECT COUNT(*) FROM query_history")
+        count = cur.fetchone()[0]
+        if count > 0:
+            actions.append(f"DELETE {count} rows FROM query_history")
+            if not dry_run:
+                cur.execute("DELETE FROM query_history")
+
+    # 3. Reset auto-increment counters
+    if not dry_run:
+        for table in ["ticket_sql_items", "ticket_approvals", "tickets"]:
+            cur.execute(f"DELETE FROM sqlite_sequence WHERE name='{table}'")
+
+    if not dry_run:
+        db.commit()
+    db.close()
+
+    return actions
+
+
+def main():
+    dry_run = "--dry-run" in sys.argv
+    if dry_run:
+        print("🔍 DRY RUN — preview only\n")
+
+    actions = cleanup(dry_run)
+
+    if not actions:
+        print("✅ 数据库干净，无需清理")
+        return
+
+    for a in actions:
+        prefix = "  WOULD " if dry_run else "  ✅ "
+        print(f"{prefix}{a}")
+
+    if dry_run:
+        print(f"\n共 {len(actions)} 项待清理 (使用不带 --dry-run 执行)")
+    else:
+        print(f"\n✅ 已清理 {len(actions)} 项")
+
+    # Print note about MySQL remote tables
+    print(f"\n⚠️  注意: 远程 MySQL 测试表需手动清理:")
+    for t in TEST_MYSQL_TABLES:
+        print(f"    DROP TABLE IF EXISTS opsxsql_test.{t};")
+
+
+if __name__ == "__main__":
+    main()