UX优化: 同步日志显示服务器名 + redis_url可编辑

- 同步日志API: JOIN Server表返回server_name字段
- 推送历史: 显示服务器名称替代操作人
- 仪表盘最近同步: 显示服务器名称替代server_id
- redis_url从SENSITIVE_KEYS移除(非密码，用户需可编辑)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/api/settings.py

@@ -24,7 +24,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 IMMUTABLE_KEYS = {"secret_key", "api_key", "encryption_key", "database_url"}
 
 # Settings whose values are masked in GET responses
-SENSITIVE_KEYS = {"secret_key", "api_key", "encryption_key", "redis_url"}
+SENSITIVE_KEYS = {"secret_key", "api_key", "encryption_key"}
 
 router = APIRouter(prefix="/api/settings", tags=["settings"])