🎨 Palette: [UX improvement] Add tooltip to speed indicator button

[JustLookAtNow]

💡 What

Wrapped the InkWell component within QbSpeedIndicator (which displays download/upload speeds) with a Flutter Tooltip widget.

🎯 Why

This interactive widget functions as an icon-only button (it displays text, but mostly technical speed data and cloud icons) and opens the downloader tasks page when clicked (_openDownloader). It previously lacked an explicit tooltip to inform users about its action, reducing discoverability.

♿ Accessibility

Added an explicit, localized semantic label ("打开下载器任务页面" / "Open Downloader Tasks Page") for the component. This provides helpful text on hover for web/desktop users and properly exposes the button's action to screen readers.

---

PR created automatically by Jules for task 10825575932682887844 started by @JustLookAtNow

[google-labs-jules]

👋 Jules, reporting for duty! I'm here to lend a hand with this pull request.

When you start a review, I'll add a 👀 emoji to each comment to let you know I've read it. I'll focus on feedback directed at me and will do my best to stay out of conversations between you and other bots or reviewers to keep the noise down.

I'll push a commit with your requested changes shortly after. Please note there might be a delay between these steps, but rest assured I'm on the job!

For more direct control, you can switch me to Reactive Mode. When this mode is on, I will only act on comments where you specifically mention me with @jules. You can find this option in the Pull Request section of your global Jules UI settings. You can always switch back!

New to Jules? Learn more at jules.google/docs.

---

For security, I will only act on instructions from the user who triggered this task.