完善后台管理与测试支撑

1、为后台用户列表增加关键词和状态筛选，后端同步支持过滤与总数统计。

2、创建用户时要求填写初始密码，并补充前端校验和自动填充隔离。

3、优化项目管理列表角色展示、项目详情抽屉脏数据保护和审计详情抽屉关闭体验。

4、清理旧费用附件关联、统一测试模型注册，并更新迁移端点和注册筛选测试。

backend/app/crud/user.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 import uuid
 from typing import Sequence
 
-from sqlalchemy import delete, func, select, update
+from sqlalchemy import delete, func, or_, select, update
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.core.config import (
@@ -79,11 +79,45 @@ async def update_user(db: AsyncSession, user: User, user_in: UserUpdate) -> User
     return user
 
 
-async def list_users(db: AsyncSession, skip: int = 0, limit: int = 100) -> Sequence[User]:
-    result = await db.execute(select(User).offset(skip).limit(limit))
+def _apply_user_filters(query, *, keyword: str | None = None, status: UserStatus | None = None):
+    if keyword:
+        pattern = f"%{keyword.strip()}%"
+        query = query.where(
+            or_(
+                User.email.ilike(pattern),
+                User.full_name.ilike(pattern),
+                User.clinical_department.ilike(pattern),
+            )
+        )
+    if status is not None:
+        query = query.where(User.status == status)
+    return query
+
+
+async def list_users(
+    db: AsyncSession,
+    skip: int = 0,
+    limit: int = 100,
+    *,
+    keyword: str | None = None,
+    status: UserStatus | None = None,
+) -> Sequence[User]:
+    query = _apply_user_filters(select(User), keyword=keyword, status=status)
+    result = await db.execute(query.order_by(User.created_at.desc()).offset(skip).limit(limit))
     return result.scalars().all()
 
 
+async def count_users(
+    db: AsyncSession,
+    *,
+    keyword: str | None = None,
+    status: UserStatus | None = None,
+) -> int:
+    query = _apply_user_filters(select(func.count()).select_from(User), keyword=keyword, status=status)
+    result = await db.execute(query)
+    return int(result.scalar_one() or 0)
+
+
 async def list_active_member_candidates_for_study(
     db: AsyncSession,
     study_id: uuid.UUID,