Folds the thirty-five [Unreleased] entries into [3.0.0] and dates it the day
it becomes installable, which is what the header at the top of this file says
its dates mean. The section was written on 2026-08-28, tagged, and never
published; develop has moved seventy-nine commits since.

Two structural defects went with the fold, both found by a documentation
review reading the file the way a consumer would:

- `### Removed` held thirteen entries, of which ten were fixes. A reader
  scanning Removed for breaking changes was reading a list of improvements.
  The two genuine removals stay; the rest are Fixed, and the label-sizing
  rule change is Changed.
- `[Unreleased]` carried two separate `### Changed` headings.

The breaking count moves from six to eight -- cover, guard and screen's base
geometry and the enum value recasing both landed after the section was
written -- and the intro now says which of the eight reach data you have
already saved, which of those are migrated on read, and which the compiler
catches for you.