fix(仪表盘): 修正分区迁移与范围测试

backend/internal/repository/usage_log_repo_integration_test.go

@@ -311,7 +311,7 @@ func (s *UsageLogRepoSuite) TestDashboardStatsWithRange_Fallback() {
 	now := time.Now().UTC()
 	todayStart := truncateToDayUTC(now)
 	rangeStart := todayStart.Add(-24 * time.Hour)
-	rangeEnd := now
+	rangeEnd := now.Add(1 * time.Second)
 
 	user1 := mustCreateUser(s.T(), s.client, &service.User{Email: "range-u1@test.com"})
 	user2 := mustCreateUser(s.T(), s.client, &service.User{Email: "range-u2@test.com"})

backend/migrations/035_usage_logs_partitioning.sql

 -- usage_logs monthly partition bootstrap.
--- Only converts to partitioned table when usage_logs is empty.
--- Existing installations with data require a manual migration plan.
+-- Only creates partitions when usage_logs is already partitioned.
+-- Converting usage_logs to a partitioned table requires a manual migration plan.
 
 DO $$
 DECLARE
@@ -20,8 +20,8 @@ BEGIN
     IF NOT is_partitioned THEN
         SELECT EXISTS(SELECT 1 FROM usage_logs LIMIT 1) INTO has_data;
         IF NOT has_data THEN
-            EXECUTE 'ALTER TABLE usage_logs PARTITION BY RANGE (created_at)';
-            is_partitioned := TRUE;
+            -- Automatic conversion is intentionally skipped; see manual migration plan.
+            RAISE NOTICE 'usage_logs is not partitioned; skip automatic partitioning';
         END IF;
     END IF;