Keeping track of what's new

A few changes for finding what's new:

The sidebar's All Posts link now shows a badge — the number of posts you haven't read yet. Open the feed and those posts are listed under "New since your last visit," each linking to its thread. Opening a post clears it from the count right away; the rest stay marked unread. If the list gets noisy, "Mark all as read" clears everything at once.

And once you've finished the welcome checklist, your home page opens with recent posts instead of the welcome page.

Behind it: one small row recording that you opened a post, visible only to the server. Your counts are private to you.