[FEATURE] Add manual page number input to Wallhaven plugin

[Yilmaz4]

Submission checklist

• I have searched existing issues and confirmed this has not been requested before.
• I have checked existing pull requests for similar changes.

Feature type

New functionality

Feature summary

Ability to enter a number for the page number instead of having to use the next page button repeatedly

Motivation / use case

Would make it easier to quickly go back to where I was if I accidentally close the panel while browsing for wallpapers

Proposed solution

Page number input

Alternatives considered

No response

References / related projects

Noctalia V4

Additional context

No response