docs: remove the hand-written Steamify section of CHANGELOG.md (the release notes are generated), TODO updated

TODO.md

@@ -19,8 +19,6 @@ Tick items off as they are done; the newest entries are at the top of each list.
       its ISO is deleted first). Watch the first time there are more than 10 releases of a kind; it hasn't run yet.
 - [ ] **Build badge, the other states**: succeeded was seen (`v2.9.6-260930`). Failed, cancelled and a build superseded by a
       newer one haven't been seen; a crashed runner leaves the badge on "running".
-- [ ] **CHANGELOG.md**: the hand-written section `## CachyOS with Steamify Live ISO` is no longer used (the release notes
-      are generated); delete it or turn it into something else.
 - [ ] **Check with the CachyOS team** whether the installer branding and the ISO file name are fine with them.
 - [ ] **Drop the Boost 1.91 workaround** in `steamify-prepare.sh` once `cachyos-calamares-next` is rebuilt against the repos' Boost.
 
@@ -42,6 +40,7 @@ Tick items off as they are done; the newest entries are at the top of each list.
       changelog section, commits since the previous release; the mirror's release uses the same text.
 - [x] **Retention** of at most 10 dev and 10 real releases, deleting the mirror's release with its ISO too (PR #22; first
       clean-up still to be seen, above).
+- [x] **Old hand-written `CHANGELOG.md` section** (`## CachyOS with Steamify Live ISO`) removed: the release notes are generated.
 - [x] **Same-day replacement of a real release** (2026-09-30): the official build for `v2.9.6-260930` replaced the test build's
       release on the mirror (ISO asset 42 -> 50, new title and generated notes, badge green with the public run link).
 - [x] **Release notes** leave out the workflow and docs commits (`ci`, `docs`, `…(ci):`) in their list of ISO changes.