fix: resolve typing test layout overlaps

[Siddhesh100711]

Summary

Fixes the responsive layout and footer issues reported in #2.

Changes

• Removed the upward relative bottom-6 offset from the top settings bar and restored normal document flow.
• Removed the upward relative bottom-5 footer offset and added proper spacing.
• Added bottom spacing to the keyboard theme selector.
• Moved the KeebKit attribution link into the footer and added spacing between the footer lines.
• Removed the old positioned KeebKit link from MainPage.jsx.

Verification

• Tested the typing test page across different viewport sizes.
• Verified the top settings bar no longer overlaps the header/content.
• Verified the keyboard theme selector has proper spacing from the footer.
• Verified the dark-theme footer no longer has the clipping/bright-line issue.
• Compared Light and Dark themes.
• npm run lint — 0 errors; 1 pre-existing warning in useTypingHandlers.js
• npm run build — passed successfully
  Closes [Bug]: Typing test layout overlaps content and clips footer #2

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[Siddhesh100711]

Hey @bilalmlkdev! The fix for #2 is ready and the PR is up. Could you please review it and let me know if any changes are needed? If everything looks good, feel free to merge it. Thanks! 🙌