Make page curl lift across full width

Replace localized spine curl with whole-page arc so the
free edge rises highest, and float the topic label with the
selected card.

src/scene/timeline.js

@@ -5,6 +5,9 @@ import { makeTextSprite } from '../utils/labels.js';
 
 export const TIMELINE_SPREAD = 6.2; // 横轴范围 ±6.2（超出视口，可横向滚动）
 
+const CARD_FLOAT = 0.14; // 选中时上浮高度
+const NAME_Y = 0.42;     // 主题标签基准高度（活页上方）
+
 function cardX(i, n) {
   return (i / (n - 1)) * 2 * TIMELINE_SPREAD - TIMELINE_SPREAD;
 }
@@ -69,18 +72,18 @@ export class Timeline {
       outline.visible = false;
       card.add(outline);
 
-      // 活页上方：主题（常显）
+      // 活页上方：主题（常显，随选中上浮）
       const name = makeTextSprite(entry.name, { fontSize: 30, color: '#e8d9b4' });
       name.scale.multiplyScalar(0.22);
-      name.position.set(x, 0.42, 0);
+      name.position.set(x, NAME_Y, 0);
 
-      // 轴下方：时间（常显）
+      // 轴下方：时间（常显，固定不动）
       const time = makeTextSprite(entry.time, { fontSize: 22, color: '#c9a227' });
       time.scale.multiplyScalar(0.18);
       time.position.set(x, -1.06, 0);
 
       this.group.add(card, name, time);
-      this.cards.push({ card, outline, index: i });
+      this.cards.push({ card, outline, name, nameBaseY: NAME_Y, index: i });
     });
   }
 
@@ -89,7 +92,8 @@ export class Timeline {
     this.cards.forEach((c) => {
       const on = c.index === index;
       c.outline.visible = on;
-      c.card.position.y = on ? 0.14 : 0;
+      c.card.position.y = on ? CARD_FLOAT : 0;
+      c.name.position.y = c.nameBaseY + (on ? CARD_FLOAT : 0);
     });
   }
 }