修复代码质量问题(Bug #20, #1, #2)

修复的Bug:
- Bug #20: 删除重复函数定义 (update_admin_username重复定义)
- Bug #1: 删除类型转换冗余 (APIBrowseResult->BrowseResult无意义转换)
- Bug #2: 统一时区处理

主要改进:
1. 删除重复函数:
   - 删除app.py:1023处重复的update_admin_username函数定义
   - 避免函数覆盖导致的潜在问题

2. 删除冗余类型转换:
   - APIBrowseResult和BrowseResult字段完全相同
   - 删除run_task中的冗余转换代码
   - 提升性能，减少维护成本

3. 统一时区处理:
   - 新增BEIJING_TZ常量和get_beijing_now()辅助函数
   - 替换所有分散的beijing_tz创建为统一函数调用
   - 删除重复的datetime/pytz导入
   - 涉及6处代码统一：
     * log_to_client - 日志时间戳
     * take_screenshot_for_account - 截图文件名
     * get_screenshots - 文件修改时间
     * run_scheduled_task - 定时任务星期检查
     * check_user_schedules - 用户定时任务检查
     * get_server_info_api - 服务器运行时长

影响:
- 提升代码质量和可维护性
- 统一时区处理，避免时间混淆
- 减少内存占用和CPU开销

受影响文件:
- app.py (所有修复)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app.py

@@ -45,6 +45,13 @@ from app_security import (
 from app_utils import verify_and_consume_captcha
 
 
+# ========== 时区辅助函数 (Bug #2 fix) ==========
+BEIJING_TZ = pytz.timezone('Asia/Shanghai')
+
+def get_beijing_now():
+    """获取北京时间的当前时间（统一时区处理）"""
+    return datetime.now(BEIJING_TZ)
+
 
 # ========== 初始化配置 ==========
 config = get_config()
@@ -312,8 +319,7 @@ def admin_required(f):
 
 def log_to_client(message, user_id=None, account_id=None):
     """发送日志到Web客户端(用户隔离)"""
-    beijing_tz = timezone(timedelta(hours=8))
+    timestamp = get_beijing_now().strftime('%H:%M:%S')
-    timestamp = datetime.now(beijing_tz).strftime('%H:%M:%S')
     log_data = {
         'timestamp': timestamp,
         'message': message,
@@ -1019,23 +1025,6 @@ def update_admin_username():
     return jsonify({"error": "修改失败，用户名可能已存在"}), 400
 
 
-
-def update_admin_username():
-    """修改管理员用户名"""
-    data = request.json
-    new_username = data.get('new_username', '').strip()
-
-    if not new_username:
-        return jsonify({"error": "用户名不能为空"}), 400
-
-    old_username = session.get('admin_username')
-    if database.update_admin_username(old_username, new_username):
-        session['admin_username'] = new_username
-        return jsonify({"success": True})
-    return jsonify({"error": "用户名已存在"}), 400
-
-
-
 # ==================== 密码重置API ====================
 
 # 管理员直接重置用户密码
@@ -1645,13 +1634,7 @@ def run_task(user_id, account_id, browse_type, enable_screenshot=True, source="m
                             browse_type=browse_type,
                             should_stop_callback=should_stop
                         )
-                        # 转换结果类型以兼容后续代码
+                        # APIBrowseResult和BrowseResult字段完全相同，无需转换
-                        result = BrowseResult(
-                            success=result.success,
-                            total_items=result.total_items,
-                            total_attachments=result.total_attachments,
-                            error_message=result.error_message
-                        )
                         api_browser.close()
                     else:
                         # API 登录失败
@@ -1984,9 +1967,7 @@ def take_screenshot_for_account(user_id, account_id, browse_type="应读", sourc
                 time.sleep(2)
 
                 # 生成截图文件名
-                beijing_tz = pytz.timezone('Asia/Shanghai')
+                timestamp = get_beijing_now().strftime('%Y%m%d_%H%M%S')
-                now_beijing = datetime.now(beijing_tz)
-                timestamp = now_beijing.strftime('%Y%m%d_%H%M%S')
 
                 user_info = database.get_user_by_id(user_id)
                 username_prefix = user_info['username'] if user_info else f"user{user_id}"
@@ -2116,8 +2097,7 @@ def get_screenshots():
                     filepath = os.path.join(SCREENSHOTS_DIR, filename)
                     stat = os.stat(filepath)
                     # 转换为北京时间
-                    beijing_tz = pytz.timezone('Asia/Shanghai')
+                    created_time = datetime.fromtimestamp(stat.st_mtime, tz=BEIJING_TZ)
-                    created_time = datetime.fromtimestamp(stat.st_mtime, tz=beijing_tz)
                     # 解析文件名获取显示名称
                     # 文件名格式：用户名_登录账号_浏览类型_时间.jpg
                     parts = filename.rsplit('.', 1)[0].split('_', 1)  # 移除扩展名并分割
@@ -2605,7 +2585,6 @@ def test_proxy_api():
 def get_server_info_api():
     """获取服务器信息"""
     import psutil
-    import datetime
 
     # CPU使用率
     cpu_percent = psutil.cpu_percent(interval=1)
@@ -2623,8 +2602,8 @@ def get_server_info_api():
     disk_percent = disk.percent
 
     # 运行时长
-    boot_time = datetime.datetime.fromtimestamp(psutil.boot_time())
+    boot_time = datetime.fromtimestamp(psutil.boot_time(), tz=BEIJING_TZ)
-    uptime_delta = datetime.datetime.now() - boot_time
+    uptime_delta = get_beijing_now() - boot_time
     days = uptime_delta.days
     hours = uptime_delta.seconds // 3600
     uptime = f"{days}天{hours}小时"
@@ -2807,17 +2786,13 @@ def run_scheduled_task(skip_weekday_check=False):
         skip_weekday_check: 是否跳过星期检查（立即执行时为True）
     """
     try:
-        from datetime import datetime
-        import pytz
-
         config = database.get_system_config()
         browse_type = config.get('schedule_browse_type', '应读')
 
         # 检查今天是否在允许执行的星期列表中（立即执行时跳过此检查）
         if not skip_weekday_check:
             # 获取北京时间的星期几 (1=周一, 7=周日)
-            beijing_tz = pytz.timezone('Asia/Shanghai')
+            now_beijing = get_beijing_now()
-            now_beijing = datetime.now(beijing_tz)
             current_weekday = now_beijing.isoweekday()  # 1-7
 
             # 获取配置的星期列表
@@ -3001,9 +2976,7 @@ def scheduled_task_worker():
         """检查并执行用户定时任务"""
         import json
         try:
-            from datetime import datetime
+            now = get_beijing_now()
-            beijing_tz = pytz.timezone('Asia/Shanghai')
-            now = datetime.now(beijing_tz)
             current_time = now.strftime('%H:%M')
             current_weekday = now.isoweekday()
 
@@ -3168,7 +3141,6 @@ def scheduled_task_worker():
             Returns:
                 UTC时间字符串，格式为 HH:MM
             """
-            from datetime import datetime, timedelta
             # 解析CST时间
             hour, minute = map(int, cst_time_str.split(':'))
             # CST是UTC+8，所以UTC时间 = CST时间 - 8小时