fix: lucky_gift_outbox delivered 保留期收紧为 7 天

线上实测 delivered 约 9 万行/天且该表无下游读方（事实在 lucky_draw_records），
30 天窗口会让表膨胀到近 300 万行；7 天足够排障。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

services/lucky-gift-service/internal/config/config.go

@@ -74,8 +74,9 @@ func Default() Config {
 			StatsRefreshInterval: 10 * time.Minute,
 			StatsBatchSize:       5000,
 			Retention: OutboxRetentionConfig{
-				Enabled:      true,
-				MaxAge:       30 * 24 * time.Hour,
+				Enabled: true,
+				// 线上 delivered 约 9 万行/天且无下游读方；7 天足够排障，30 天会让表膨胀到近 300 万行。
+				MaxAge:       7 * 24 * time.Hour,
 				ScanInterval: 5 * time.Minute,
 				BatchSize:    500,
 			},

services/lucky-gift-service/internal/config/config_test.go

@@ -17,8 +17,8 @@ func TestLoadDefaultsEnableOutboxRetention(t *testing.T) {
 	if !retention.Enabled {
 		t.Fatal("retention should be enabled by default")
 	}
-	if retention.MaxAge != 30*24*time.Hour {
-		t.Fatalf("retention.MaxAge = %s, want 720h", retention.MaxAge)
+	if retention.MaxAge != 7*24*time.Hour {
+		t.Fatalf("retention.MaxAge = %s, want 168h", retention.MaxAge)
 	}
 	if retention.ScanInterval != 5*time.Minute {
 		t.Fatalf("retention.ScanInterval = %s, want 5m", retention.ScanInterval)

services/lucky-gift-service/internal/service/luckygift/outbox_retention.go

@@ -23,9 +23,10 @@ type OutboxRetentionOptions struct {
 
 func defaultOutboxRetentionOptions() OutboxRetentionOptions {
 	// 默认值和 config.Default 的 retention 保持一致，防止手动构造绕过配置归一化后误删新事件。
+	// 线上 delivered 约 9 万行/天且无下游读方，7 天窗口在可排障和表体积之间取平衡。
 	return OutboxRetentionOptions{
 		ScanInterval: 5 * time.Minute,
-		MaxAge:       30 * 24 * time.Hour,
+		MaxAge:       7 * 24 * time.Hour,
 		BatchSize:    500,
 	}
 }