docs(changelog): trim the rollup to one line per change, linked

The operator's read: right content, too many words. Every rollup
bullet is now a bold lead plus one sentence, closing with links to
the commits that shipped it — 48 links, each verified to resolve and
to sit on origin/v1. The flags and verbs a reader must type all
survive; the rationale lives on in the per-release entries below.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>