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

Reorganize internal packages into platform/infra/shared layers and update
imports, docs, and seed-count tests to match current system configs.

internal/infra/task/permanent_error_test.go

@@ -0,0 +1,27 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package task
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/hibiken/asynq"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPermanentErrorSkipsRetryWithoutExposingAsynqMessage(t *testing.T) {
+	err := PermanentError("  来源配置无效  ")
+
+	assert.True(t, errors.Is(err, asynq.SkipRetry))
+	assert.Equal(t, "来源配置无效", err.Error())
+	assert.NotContains(t, err.Error(), asynq.SkipRetry.Error())
+}
+
+func TestPermanentErrorUsesSafeFallbackForBlankMessage(t *testing.T) {
+	err := PermanentError("  ")
+
+	assert.True(t, errors.Is(err, asynq.SkipRetry))
+	assert.Equal(t, defaultPermanentErrorMessage, err.Error())
+}