[FEATURE]: home returns to where end left a scrolled-up reader #53629

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

When you are scrolled up reading an older part of a session and jump to the bottom with end (messages_last), to read new output or to type a prompt, the place you were reading is lost. Getting back means scrolling and looking for it again.

Proposal: messages_last remembers where a scrolled-up reader was, and the next messages_first (home) returns there instead of going to the top. Pressing messages_first again goes to the top, as today. So end then home is a round trip, and home home still reaches the top.

The remembered position is the block that was at the top of the viewport, plus its offset from that edge, so it stays correct when content above or below it changes. It is dropped, and home goes to the top as today, when:

• it was taken in another session;
• the view has moved off the bottom by the time home is pressed;
• any other navigation command ran in between (page, half page, line, prompt, landmark or block navigation, last user message), or the transcript was scrolled with the wheel;
• its block is no longer rendered, for example after a revert.

Pressing end again at the bottom keeps the position it already holds, so new output or a submitted prompt in between does not lose it.