feat(ops): add usage_logs partitioning check at deployment startup

Add CheckUsageLogsPartitioning function that:
- Checks if usage_logs table is partitioned
- Warns with prominent banner if not partitioned and rows > 100K
- Provides actionable guidance for manual partition migration

This helps operators identify performance risks early and take
appropriate action before data volume causes issues.

backend/internal/repository/migrations_runner.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
+	"log"
 	"sort"
 	"strings"
 	"time"
@@ -432,3 +433,51 @@ func pgAdvisoryUnlock(ctx context.Context, db *sql.DB) error {
 	}
 	return nil
 }
+
+// CheckUsageLogsPartitioning 检查 usage_logs 表是否已分区。
+// 如未分区且数据量较大，会输出醒目的警告提示运维人员考虑分区。
+func CheckUsageLogsPartitioning(ctx context.Context, db *sql.DB) {
+	var isPartitioned bool
+	err := db.QueryRowContext(ctx, `
+		SELECT EXISTS(
+			SELECT 1
+			FROM pg_partitioned_table pt
+			JOIN pg_class c ON c.oid = pt.partrelid
+			WHERE c.relname = 'usage_logs'
+		)
+	`).Scan(&isPartitioned)
+	if err != nil {
+		// 查询失败时静默忽略，不影响启动
+		return
+	}
+
+	if isPartitioned {
+		return
+	}
+
+	// 检查数据量
+	var rowCount int64
+	err = db.QueryRowContext(ctx, `SELECT COUNT(*) FROM usage_logs`).Scan(&rowCount)
+	if err != nil {
+		return
+	}
+
+	// 数据量小于 10 万行时，分区不那么紧急
+	if rowCount < 100000 {
+		return
+	}
+
+	// 数据量较大且未分区，输出醒目警告
+	log.Printf("================================================================================")
+	log.Printf("⚠️  PERFORMANCE WARNING: usage_logs table is NOT partitioned")
+	log.Printf("    Current rows: %d (threshold: 100,000)", rowCount)
+	log.Printf("    Large unpartitioned tables can cause:")
+	log.Printf("      - Slow queries and dashboard latency")
+	log.Printf("      - Index bloat and maintenance overhead")
+	log.Printf("      - Longer backup/restore times")
+	log.Printf("    Recommended actions:")
+	log.Printf("      1. Review migrations/035_usage_logs_partitioning.sql for manual migration")
+	log.Printf("      2. Plan partition conversion during low-traffic window")
+	log.Printf("      3. Ensure UsageCleanupConfig is enabled for automatic cleanup")
+	log.Printf("================================================================================")
+}

backend/internal/setup/setup.go

@@ -362,7 +362,13 @@ func initializeDatabase(cfg *SetupConfig) error {
 
 	migrationCtx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
 	defer cancel()
-	return repository.ApplyMigrations(migrationCtx, db)
+	if err := repository.ApplyMigrations(migrationCtx, db); err != nil {
+		return err
+	}
+
+	// 检查 usage_logs 分区状态（仅在首次部署时提示）
+	repository.CheckUsageLogsPartitioning(migrationCtx, db)
+	return nil
 }
 
 func createAdminUser(cfg *SetupConfig) (bool, string, error) {