重构数据库备份与恢复模块 (#80)

* fix: 保存 LastResult 时截断字符串过长部分，以避免数据库报错

* refactor: 新增 entity.DbTaskBase 和 persistence.dbTaskBase, 用于实现数据库备份和恢复任务处理相关部分

* fix: aeskey变更后，解密密码出现数组越界访问错误

* fix: 时间属性为零值时，保存到 mysql 数据库报错

* refactor db.infrastructure.service.scheduler

* feat: 实现立即备份功能

* refactor db.infrastructure.service.db_instance

* refactor: 从数据库中获取数据库备份目录、mysql文件路径等配置信息

* fix: 数据库备份和恢复问题

* fix: 修改 .gitignore 文件，忽略数据库备份目录和数据库程序目录

server/pkg/utils/timex/timex_test.go

@@ -0,0 +1,77 @@
+package timex
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+	"time"
+)
+
+func TestNullTime_UnmarshalJSON(t *testing.T) {
+	zero := time.Time{}
+	now := time.Now()
+	bytesNow, err := now.MarshalJSON()
+	require.NoError(t, err)
+	tests := []struct {
+		name    string
+		want    NullTime
+		bytes   []byte
+		wantErr error
+	}{
+		{
+			name:  "zero",
+			want:  NewNullTime(zero),
+			bytes: nil,
+		},
+		{
+			name:  "now",
+			want:  NewNullTime(now),
+			bytes: bytesNow,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := &NullTime{}
+			err := got.UnmarshalJSON(tt.bytes)
+			require.ErrorIs(t, err, tt.wantErr)
+			if err != nil {
+				return
+			}
+			require.Equal(t, tt.want.Valid, got.Valid)
+			require.True(t, got.Time.Equal(tt.want.Time))
+		})
+	}
+}
+
+func TestNullTime_MarshalJSON(t *testing.T) {
+	zero := time.Time{}
+	now := time.Now()
+	bytes, err := now.MarshalJSON()
+	require.NoError(t, err)
+	tests := []struct {
+		name     string
+		nullTime NullTime
+		want     []byte
+		wantErr  error
+	}{
+		{
+			name:     "zero",
+			nullTime: NewNullTime(zero),
+			want:     []byte("null"),
+		},
+		{
+			name:     "now",
+			nullTime: NewNullTime(now),
+			want:     bytes,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.nullTime.MarshalJSON()
+			require.ErrorIs(t, err, tt.wantErr)
+			if err != nil {
+				return
+			}
+			require.Equal(t, tt.want, got)
+		})
+	}
+}