Add feature to jump to a specific page

[Diginaut]

This pull request introduces a new feature that allows users to jump to a specific page number. The feature has been implemented in the footer section.

Changes:

• Added a page input field in the footer to allow direct page navigation.
• Implemented functionality to validate and process user input.

Issue Reference:
This PR addresses issue #22.

Testing:

• Manually tested the feature with the default IIIF import.
• Verified edge cases such as invalid inputs and out-of-range numbers.

[DennisFriedl]

This still needs some work. Please don't merge yet.

[DennisFriedl]

Looks good!