fix: 修复 AI Code Review 阻塞级问题

1. assets.py: 修复高频排除回退逻辑 min(limit,1) → limit
2. assets.py: high_use_excluded 改用 set 提升查找效率
3. dedup.py: compute_duplicate_rate 限制查询最近100个视频避免OOM
4. 更新单元测试适配新的查询方式

apps/api/app/api/routes/assets.py

@@ -619,7 +619,7 @@ def smart_match_assets(
                     asset_ids=asset_ids,
                     recent_video_count=5,
                 )
-                high_use_excluded = []
+                high_use_excluded = set()
                 for r in filtered_results:
                     aid = getattr(r.asset, "id", "")
                     count = use_counts.get(aid, 0)
@@ -628,12 +628,12 @@ def smart_match_assets(
                             "smart-match 排除高频使用素材: asset_id=%s use_count=%d limit=%d",
                             aid, count, MAX_RECENT_USE_COUNT,
                         )
-                        high_use_excluded.append(r)
+                        high_use_excluded.add(id(r))
                     else:
                         pass
                 # 如果排除后不够 limit，放宽到不限制
-                remaining = [r for r in filtered_results if r not in high_use_excluded]
-                if len(remaining) >= min(request.limit, 1):
+                remaining = [r for r in filtered_results if id(r) not in high_use_excluded]
+                if len(remaining) >= request.limit:
                     filtered_results = remaining
                 else:
                     logger.info("smart-match 高频排除后素材不足(%d<%d)，保留全部", len(remaining), request.limit)