feat(timeline): P1 白模演出预览——时间线+俯视舞台播放

- /api/pointsets 增 anchors(含 pos/rot/kind/npc 坐标)，保留 points 名字数组兼容下拉
- 新增 static/timeline.js：线性化主路径→按时长铺多轨时间线 + 2D 俯视白模舞台播放
  (走位插值/对话打字机/镜头俯视框示意/playhead/点击跳转)；战斗/选择/随机仅标点不模拟
- 工具栏加「演出预览」按钮 + 预览遮罩 + 暗金主题样式
- 时长模型：对话=字数×打字机速度，走位=坐标距离÷速度，动画/镜头给缺省时长
- node 离线测试两样张(含 out_ref+fight+skip)逻辑全过；修掉结局重复渲染 bug

设计文档见主仓 docs/plans/2026-06-13-story-timeline-editor-and-whitebox-preview-design.md (P1 期)

web/app.py

@@ -163,9 +163,21 @@ async def pointsets():
                 try:
                     with open(os.path.join(_POINTSETS_DIR, fn), encoding="utf-8") as f:
                         ps = json.load(f)
+                    pts = ps.get("points", [])
                     out[name] = {
                         "mapId": ps.get("mapId", ""),
-                        "points": [p.get("name") for p in ps.get("points", [])],
+                        "points": [p.get("name") for p in pts],   # 名字数组：兼容现有表单下拉
+                        # 含坐标的锚点：白模演出预览用（map-local pos[x,y,z] + rot）
+                        "anchors": [
+                            {
+                                "name": p.get("name"),
+                                "pos": p.get("pos") or [0, 0, 0],
+                                "rot": p.get("rot", 0),
+                                "kind": p.get("kind", ""),
+                                "npc": p.get("npc", ""),
+                            }
+                            for p in pts
+                        ],
                     }
                 except Exception as e:
                     out[name] = {"error": str(e)}