fix(home): server-owned growth window; expose days

Home omits growth_days; backend auto (or home_growth_days 1/7) picks
the window. Response includes days alongside growth_days. Growth榜 link
uses the returned days. Non-growth sorts treat omitted/auto as 7.

tests/test_web_queries.py

@@ -106,6 +106,8 @@ def test_growth_and_cold_start():
         try:
             growth = q.list_videos(sort="growth", growth_days=2)
             assert growth["available"] is True
+            assert growth["days"] == 2
+            assert growth["growth_days"] == 2
             assert {item["aid"] for item in growth["items"]} == {101, 102}
             first = next(item for item in growth["items"] if item["aid"] == 101)
             assert first["growth"]["available"] is True
@@ -570,15 +572,19 @@ def test_growth_auto_falls_back_to_one_day():
     with tempfile.TemporaryDirectory() as tmp:
         db, q = setup(tmp)
         try:
-            auto = q.list_videos(sort="growth", growth_days="auto", page_size=6)
+            # 省略 growth_days 与显式 auto 等价：后端决定窗口并回传 days
+            auto = q.list_videos(sort="growth", page_size=6)
             assert auto["available"] is True
             assert auto["growth_days"] == 1
+            assert auto["days"] == 1
             assert {item["aid"] for item in auto["items"]} == {101, 102}
             first = next(item for item in auto["items"] if item["aid"] == 101)
             assert first["growth"]["delta"] == 100  # 相邻日
 
             forced7 = q.list_videos(sort="growth", growth_days=7)
             assert forced7["available"] is False
+            assert forced7["days"] == 7
+            assert forced7["growth_days"] == 7
             assert "至少 8 天快照" in forced7["reason"]
 
             # 配置钉死 7 天：auto 不再降级
@@ -589,8 +595,9 @@ def test_growth_auto_falls_back_to_one_day():
             target = max(path.stat().st_mtime_ns, time.time_ns()) + 1_000_000
             os.utime(path, ns=(target, target))
             DASHBOARD_CACHE.clear()
-            pinned = q.list_videos(sort="growth", growth_days="auto")
+            pinned = q.list_videos(sort="growth")  # omit → auto → 配置钉死 7
             assert pinned["growth_days"] == 7
+            assert pinned["days"] == 7
             assert pinned["available"] is False
         finally:
             db.close()