docs(release): release from tags with selected cherry-picks while main stays open (#8188)

Replace the next-branch discipline with the main-first workflow: normal PRs
always merge into main, each release builds in a short-lived release workspace
from origin/main or a release tag plus approved cherry-picks, promotions take
an inventory that defaults to defer, and a reconcile PR brings the shipped
changelog, version and F-Droid files back into main.

.github/workflows/ci.yml

@@ -3,7 +3,7 @@ name: CI
 on:
   push:
     branches: [main]
-  # Every base branch, so stacked PRs and PRs into `next` get the same checks.
+  # Every base branch, so stacked PRs and PRs into any base get the same checks.
   pull_request:
   merge_group:
   workflow_dispatch: