feat: preserve catalogue pagination when returning from details

[AlsoNotMehh]

Changes

• Store the current catalogue page and route in sessionStorage.
• Restore the saved page when returning from repository details.
• Use the saved catalogue route for the details back link.
• Fall back safely to #/home when the stored route is missing or invalid.
• Add unit coverage for page persistence and return-route handling.

Context

This moves the fix from azerothcore/azerothcore.github.io#183 into the catalogue source repository, as requested by the maintainer.

[Helias]

thank you!