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.

reaction_board/web/static/views/home.js

@@ -47,8 +47,8 @@ export async function renderHome(root) {
     api("/api/overview"),
     api("/api/videos", { sort: "published", within_days: 14, limit: 6 }),
     api("/api/videos", { sort: "heat", limit: 6 }),
-    // auto：服务端按 analytics.home_growth_days 解析；默认先试 7 天再降到 1 天
-    api("/api/videos", { sort: "growth", growth_days: "auto", limit: 6 }),
+    // 不带天数：后端按 home_growth_days（默认 auto：有 7 日则 7，否则 1）决定，响应带 days
+    api("/api/videos", { sort: "growth", limit: 6 }),
   ]);
 
   const fans = overview.fans;
@@ -60,7 +60,8 @@ export async function renderHome(root) {
   const pending = overview.counts?.candidates_pending || 0;
   // 候选提示仅对已登录（或未启用鉴权）用户可见，访客不展示运行期信息。
   const showCandidates = pending > 0 && canAccessProtected();
-  const growthDays = Number(growth.growth_days) || 1;
+  // 以后端返回的 days（与 growth_days 同步）为准，避免前端再探查
+  const growthDays = Number(growth.days ?? growth.growth_days) || 1;
   const growthLabel = `近 ${growthDays} 日`;
   const growthEmptyTitle = growth.reason
     || `近 ${growthDays} 日增长暂不可用`;