Post Author & Date Changer 1.0.0

Change who wrote a post and when it was posted, from the post's own "•••" menu. Thread starters, post
order, last-post info, message counts and reactions are all kept in sync.

Imported posts credited to the wrong account, a guest post that should belong to a member, an
announcement that needs to be dated for the day it went live: fixing any of these normally means
database surgery. Post Author & Date Changer makes it a two-click moderator action.

Every post gets a "Change author / date" item in its "•••" menu. It opens a small form:

- **Author:** start typing a member's name. For imported content, you can also post under a name that
isn't a member, as a guest.
- **Date and time:** enter the new date and time in your own time zone.

The add-on then updates everything that depends on the author and date, not just the post:

- If it's the thread's first post, the thread's starter and start date follow.
- Posts are re-ordered by date.
- The thread's and forum's "last post" details are rebuilt.
- One message moves from the old author to the new one, along with the reaction score the post earned.
- The "you've posted in this thread" markers, the search index and the moderator log are updated too.

Safety rules keep threads consistent: a reply can't be dated before the first post, the first post can't
be dated after a reply, and nothing can be dated in the future.

Two moderator permissions, "Change post author" and "Change post date and time", can be granted
separately and per forum.