Continuous draft releases, not stateless on-demand generation

Tools like git-cliff are stateless: invoke against a commit range, print notes, done. We instead mirror Release Drafter's model — a live draft release is created/updated on the backend on every push to the default branch, finalized by a human (or draftsman publish) later. This was chosen because GitHub, Gitea, and Forgejo release APIs all support a draft flag, so the "always-current draft, human publishes" workflow is portable across all three backends without any backend-specific compromise.

Consequences

Generation and publishing are separate concerns — draftsman draft upserts the draft, publishing is a distinct step (backend UI or draftsman publish). A purely stateless tool would not need this split, but would also lose the "draft is always current" property that was the actual goal.

Update: GitLab has no draft flag on releases — this ADR's "portable across all backends without compromise" claim held for the original three, not for GitLab's adapter (added later), which approximates a draft via the "Upcoming Release" mechanism instead. See ADR-0005.