Inconsistent implementation and documentation of the 'skeleton sweep' UI animation in open-claude-ui.

Following the token-desync work in #16 and the pure-CSS layer in #17, the skeleton sweep looks like the same class of problem but one layer deeper: the token layer ships a keyframe nobody consumes, `cds-pure.css` advertises a utility it doesn't contain, and the one consumer in the repo disagrees with the forensic record on every parameter.

I can't check any of this against the real desktop app — I'm on Linux, so I have no artifact to compare with. Everything below is strictly internal consistency, and the call on which value is ground truth is yours.

### 1. The only consumer diverges on all three parameters

`code-examples/cds-theme.css:451` records the forensic values in a comment:

```css
/* 8. 骨架屏高级倾斜扫光 (REA 取证：2s linear 105deg) */
@keyframes cds-skeleton-sweep { 0% { transform: translate(-100%); } 100% { transform: translate(100%); } }
```

The keyframe carries only the translation; duration, easing and gradient angle live at the call site. Three sources agree with the comment, one doesn't:

| source | duration | easing | angle |
|---|---|---|---|
| `cds-theme.css:451` (REA 取证 comment) | 2s | linear | 105° |
| `docs/v2/03-架构重构与对比分析.md:150` | — | linear | 105° |
| `docs/v2/05-生产级参考实现代码.md:286,294` | `sweep_2s_infinite` | — | `linear-gradient(105deg, …)` |
| **`docs/claude-components-storybook.html:360-361`** | **1.8s** | **cubic-bezier(0.4, 0, 0.2, 1)** | **90°** |

```css
/* storybook:360-361 */
background: linear-gradient(90deg, transparent 0%, rgba(255,255,255,0.4) 50...