feat: 行程活动拖拽排序 + 编辑表单（含高德 POI 搜索）

- 安装 @dnd-kit/core/sortable/utilities/modifiers
- BlindboxPlan: 同天内拖拽排序（PointerSensor + TouchSensor，限垂直轴）
- BlindboxPlan: 点击编辑弹出 sheet modal，支持改时间（type=time）、时长、活动名
- BlindboxPlan: POI 字段改为高德 inputtips 搜索下拉，选中自动填入名称/地址/坐标
- BlindboxPlan: 搜索传入房间坐标 location 参数，结果按距离排序
- BlindboxPlan: 跨天移动通过 select 立即生效
- plan route: 新增 update_plan action，支持 PATCH 保存修改后的 days
- page.tsx: 新增 handlePlanDaysChange，乐观更新本地 state + 失败时回滚

src/app/blindbox/[code]/page.tsx

@@ -606,6 +606,27 @@ export default function BlindboxRoomPage() {
     router.refresh();
   }, [router]);
 
+  const handlePlanDaysChange = useCallback(async (newDays: WeekendPlanData[]) => {
+    if (!planId || !profile) return;
+    const prevDays = planDays;
+    setPlanDays(newDays);
+    if (planAccepted) {
+      setActiveContract((prev) => prev ? { ...prev, days: newDays } : prev);
+    }
+    try {
+      const res = await fetch("/api/blindbox/plan", {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ planId, userId: profile.id, action: "update_plan", days: newDays }),
+      });
+      if (!res.ok) throw new Error((await res.json().catch(() => ({}))).error || "保存失败");
+    } catch (e) {
+      setPlanDays(prevDays);
+      if (planAccepted) setActiveContract((prev) => prev ? { ...prev, days: prevDays } : prev);
+      toast.show(e instanceof Error ? e.message : "保存失败");
+    }
+  }, [planId, profile, planDays, planAccepted, toast]);
+
   /** Non-creator: leave room (remove membership). Creator: delete room (after confirm). */
   const handleLeaveOrDelete = async () => {
     if (!confirmLeave) {
@@ -1090,6 +1111,8 @@ export default function BlindboxRoomPage() {
                   days={planDays}
                   accepted={planAccepted}
                   regenerating={generating}
+                  onDaysChange={handlePlanDaysChange}
+                  location={room.lng != null && room.lat != null ? `${room.lng},${room.lat}` : undefined}
                   onAccept={async () => {
                     setPlanAccepted(true);
                     fireConfetti();