Save target address before redirecting

What does this MR do and why?

We introduced a new feature in a previous MR: jump to the SaaS landing page when not logged in.

Here is an optimization for it: After users log in, they can automatically jumps back to the address originally visited.

Screenshots or screen recordings

No UI changes.

How to set up and validate locally

Same as: !1473 (merged)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.