Disable auto append new status

[null2264]

Similar to Pleroma-FE/Akkoma-FE's "Show More" behaviour, new statuses will be shown after the user clicks a button instead of automatically displayed when the user's screen is at the top of the page.

This should improve UI/UX when navigating the "Fediverse" page.

• Going to the top of the page shouldn't make new posts automatically displayed fixed in 4d19806 (It'll auto append when user is at the top of the page for certain amount of time)
• Changed scroll top button to show new post's authors
• Add "Show n post(s)" button below compose form (above post list)
• The old "Click to see n new posts" button when new posts detected should act the same as "Show n post(s)" button

REF: https://git.joinfirefish.org/firefish/firefish/-/merge_requests/10513