fix: 回应 Codex review——复制反馈仅在写入成功时显示；插件名改为 window.open 按钮

- copy 现在 await writeClipboard 的布尔结果，剪贴板被拒时不再显示「已复制」（避免误导用户粘贴从未写入的命令）
- 插件名由 <a target=_blank> 改为 <button>，与「跳转」按钮同走 window.open——锚点会被 document capture 的链接接管拦截（忽略 target=_blank）开进侧边栏浏览器，按钮形态绕过
- 测试：新增剪贴板拒绝用例 + 名字/跳转双按钮 window.open 断言

src/client/SideCardSection.module.css

@@ -555,16 +555,26 @@
   outline-offset: 1px;
 }
 
+/* The plugin name: a BUTTON (not an anchor — an anchor would be caught by
+   the sidebar link takeover at document capture, ignoring target=_blank)
+   styled like a link; opens the repo in a real new browser tab. */
 .pluginName {
+  appearance: none;
   min-width: 0;
+  padding: 0;
+  border: 0;
+  background: transparent;
+  font: inherit;
   font-size: 13px;
   line-height: 20px;
   font-weight: 600;
   color: var(--dsw-alias-label-primary);
+  text-align: left;
   text-decoration: none;
   overflow: hidden;
   text-overflow: ellipsis;
   white-space: nowrap;
+  cursor: pointer;
 }
 
 .pluginName:hover {