fix: v0.14.3 GenerationRecord 加 updated_at + 轮询改固定5秒

- GenerationRecord 加 updated_at 字段（之前只在 QuotaConfig 上，Celery 查 GenerationRecord 报 FieldError）
- 后端轮询间隔从渐进式（5s→15s→30s）改为全程固定 5 秒（RPM 12000 足够，400 并发仅用 40%）

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/apps/generation/models.py

@@ -48,6 +48,7 @@ class GenerationRecord(models.Model):
     is_favorited = models.BooleanField(default=False, verbose_name='已收藏')
     seed = models.BigIntegerField(default=-1, verbose_name='种子值')
     created_at = models.DateTimeField(auto_now_add=True, db_index=True, verbose_name='创建时间')
+    updated_at = models.DateTimeField(auto_now=True, verbose_name='更新时间')
     completed_at = models.DateTimeField(null=True, blank=True, verbose_name='完成时间')
 
     class Meta:

backend/apps/generation/tasks.py

@@ -7,15 +7,8 @@ from celery import shared_task
 
 logger = logging.getLogger(__name__)
 
-# 渐进式轮询间隔
-# 前 2 分钟：每 5 秒    (24 次)
-# 2-10 分钟：每 15 秒   (32 次)
-# 10 分钟后：每 30 秒   (无限)
-POLL_SCHEDULE = [
-    (120, 5),     # 0-120s: every 5s
-    (600, 15),    # 120-600s: every 15s
-    (None, 30),   # 600s+: every 30s
-]
+# 固定轮询间隔：全程每 5 秒（RPM 12000 足够，400 并发仅用 40%）
+POLL_INTERVAL = 5
 
 
 @shared_task(bind=True, max_retries=0, ignore_result=True)
@@ -49,15 +42,8 @@ def poll_video_task(self, record_id):
     logger.info('poll_video_task: start polling record=%s ark=%s', record_id, ark_task_id)
 
     while True:
-        # 计算当前间隔
-        interval = POLL_SCHEDULE[-1][1]  # default to last
-        for threshold, iv in POLL_SCHEDULE:
-            if threshold is None or elapsed < threshold:
-                interval = iv
-                break
-
-        time.sleep(interval)
-        elapsed += interval
+        time.sleep(POLL_INTERVAL)
+        elapsed += POLL_INTERVAL
 
         # Re-fetch record to check if frontend already updated it
         try: