release: cargo-release config for tag-driven releases

`cargo release patch --execute` now does what the last three releases
did by hand: bump Cargo.toml/Cargo.lock, rewrite PKGBUILD's pkgver,
stamp the "## Unreleased" changelog section with version and date,
commit as "release X.Y.Z", tag vX.Y.Z and push commit and tag to the
gitea remote (not `origin`, which is the GitHub upstream). The tag then
triggers .gitea/workflows/release.yml as before. No crates.io publish.

CHANGELOG.md gets a standing "## Unreleased" section to collect entries
between releases; README documents the flow.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

release.toml

@@ -0,0 +1,26 @@
+# cargo-release settings. Cut a release with
+#
+#     cargo release patch          # dry run, shows what would change
+#     cargo release patch --execute
+#
+# (or `minor`, `major`, or an explicit version). It bumps Cargo.toml and
+# Cargo.lock, rewrites PKGBUILD's pkgver, turns the "## Unreleased"
+# section of CHANGELOG.md into "## X.Y.Z (date)", commits, tags
+# vX.Y.Z and pushes commit + tag to the gitea remote. That tag is what
+# .gitea/workflows/release.yml builds and uploads to the [uhhm] registry.
+
+# Not on crates.io; the package goes to the Arch registry via the tag.
+publish = false
+# `origin` is the upstream kennylevinsen fork on GitHub; releases go to
+# project.uhhm.no, and the workflow only runs there.
+push-remote = "gitea"
+allow-branch = ["master"]
+tag-name = "v{{version}}"
+tag-message = "wldash {{version}}"
+pre-release-commit-message = "release {{version}}"
+
+pre-release-replacements = [
+  { file = "PKGBUILD", search = "^pkgver=.*", replace = "pkgver={{version}}", exactly = 1 },
+  { file = "PKGBUILD", search = "^pkgrel=.*", replace = "pkgrel=1", exactly = 1 },
+  { file = "CHANGELOG.md", search = "^## Unreleased$", replace = "## {{version}} ({{date}})", exactly = 1 },
+]