Align 404 page with global UI and themebug:

Description

The current 404 page does not consistently match the application's global UI and theme.

The page should reuse the existing application layout and styling conventions so that it remains visually consistent with the rest of CreatorOS. It should also correctly respect the application's light and dark theme settings.

Proposed changes

• Align the 404 page with the application's existing global layout.
• Reuse existing UI components and styling patterns where appropriate.
• Ensure the page correctly responds to the active light/dark theme.
• Maintain responsive behavior across supported screen sizes.
• Avoid introducing duplicate styling or components when existing project components can be reused.

Validation

• Verify the 404 page in both light and dark themes.
• Verify the page at different viewport sizes.
• Ensure navigation back to the application continues to work correctly.
• Run the relevant project checks and tests before submitting the pull request.

Contribution

I would like to take ownership of this issue and implement the proposed changes. If approved, I will submit a focused pull request referencing this issue.