refactor(structure): group platform, infra, and shared packages

Move process wiring, technical adapters, and cross-cutting contracts out of flat internal/ packages so new code has a clear home without changing business layout.

internal/infra/task/constants.go

@@ -0,0 +1,14 @@
+// Copyright 2025 linux.do
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+// Package task 定义异步任务类型与调度常量
+package task
+
+// 任务队列名称
+const (
+	QueueDefault = "default"
+)
+
+// DefaultMaxRetry 任务默认最大重试次数
+const DefaultMaxRetry = 3