optimize: community polish — crossfade, position lock, effort sync

- 双图层交叉淡化人像过渡：备用层加载完成才淡入，无白闪；拖动 120ms 快速过渡、落定 340ms 慢速过渡，prefers-reduced-motion 直切
- 滑块位置固定：原生模型座位按钮级 180px 固定足迹（选择器限定 button，避免误伤 label/effort 子元素）+ 滑块 flex 固定尺寸 + 交互期 rAF 漂移补偿
- 原生推理等级与滑块实时同步：拖动预览乐观回写共享 directory store，松手提交、失败/Esc/取消自动回滚
- 滑动更丝滑：移除图片序列模式下对隐藏 video 的每帧 seek，24 张锚点预加载 + decoding=async，交叉淡化走合成器动画
- 滑块自定义光标：liang-cursor.cur（热点居中 16,16），加载失败回退 ew-resize
- 版本升至 0.2.0，随包新增 CHANGELOG.md 优化说明

package.json

@@ -1,8 +1,8 @@
 {
   "name": "dsh-client-liang-intensity-skin",
-  "version": "0.1.5",
+  "version": "0.2.0",
   "private": true,
-  "description": "滑动变祖：an opt-in adaptive reasoning slider skin for DeepSeek Harness",
+  "description": "滑动变祖（社区优化版）：an opt-in adaptive reasoning slider skin for DeepSeek Harness",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/kingOfSoySauce/dsh-liang-skin.git"
@@ -17,6 +17,8 @@
     "./package.json": "./package.json"
   },
   "files": [
+    "assets/liang-cursor.cur",
+    "assets/liang-cursor.ico",
     "assets/liang-evolution.mp4",
     "assets/liang-evolution.webm",
     "assets/liang-poster.png",
@@ -44,6 +46,7 @@
     "assets/portrait-source-v2/level-28.png",
     "assets/portrait-source-v2/level-29.png",
     "assets/portrait-source-v2/stage-30.png",
+    "CHANGELOG.md",
     "cordis.patch.yml",
     "lib/client.js",
     "lib/client.js.map",