菜单栏无内容时保持空白

[1254455745]

这个 PR 调整菜单栏无内容时的展示逻辑。

改动内容：

• 当用户关闭所有菜单栏内容时，不再显示“加载中”。
• 空内容保持空白，符合用户主动关闭显示项的预期。
• 调整滚动、轮播、固定相关视图的空内容宽度处理。

验证：

• 单独分支构建通过。

[pullfrog]

✅ No new issues found.

Reviewed changes — single commit replacing the "Loading..." placeholder with a blank empty state when users close all menu bar display items.

• Replace placeholder text — TickerRenderer.render(items:) returns NSAttributedString() instead of the localized "ticker.empty" string when items are empty.
• Reserve minimal click target — TickerView, CarouselTickerView, and CompactTickerView all return 24px from totalWidth when content is empty, preserving a small hit area for the status item without displaying any text.
• Trim stale reserved width — TickerView.update(attributed:) resets visibleTextWidth to 0 when the string is empty, preventing a false 280px text region from persisting in the layout.
• Show zero-value assets — CompactTickerView.renderPieces() no longer skips totalAssets when the value is exactly 0, consistent with the user's toggle preference.

  ^{｜ View workflow run ｜ Using DeepSeek Flash ｜ 𝕏}

[TNT-Likely]

@1254455745 多谢拆分提交!这个 PR 目前和 main 有冲突了 —— #15 / #18(自动宽度)/ #21 / #22 已经合入 main,和本 PR 改动了同一批菜单栏 ticker 文件,所以产生了冲突。麻烦 rebase 到最新 main、解决冲突后再推一下,我这边复测通过就合入。🙏

[1254455745]

重新提交啦，你看看～