Fix release changelog range and attach RPM + checksums (#18)

## Why

The `v0.5.4` release step failed with `Error: open node-lookup-linux-amd64: no such file or directory`, so the Gitea releases page carries **none** of the binaries. Root cause: at v0.5.4 the build loop's shell variables (`${name}`, `${pkg}`, `${osarch%/*}`) were unescaped, so Woodpecker substituted them to empty at YAML-parse time and no cross-compiled binaries were produced. The same blanking left the release `--note` empty (`git log "..v0.5.4"`).

The build-loop escaping was already fixed in #16. This PR fixes the two remaining release-step defects and enriches the release assets.

## Changes

- Replace the `git describe --tags --abbrev=0 HEAD^` changelog anchor with a previous-tag scan that skips tags on the current commit and picks the newest semver **ancestor** tag. Several tags point at the same commit (v0.5.3 and v0.5.4 both on `f296056`), so `describe HEAD^` jumps the range back to v0.5.1; the scan correctly selects v0.5.2.
- Attach the packaged RPM (from `dist/`) and a generated `sha256sums.txt` alongside the 12 cross-compiled binaries.
- Build the asset list once and checksum exactly what is uploaded.

Keeps `serviceAccountName: default` and the k8s resource requests/limits on the release step unchanged.

## Validation

- `check-yaml` / `trailing-whitespace` pre-commit hooks pass.
- Local dry-run of the exact release-step shell logic (with `$$`→`$`) from the worktree: `PREV_TAG=v0.5.2`, non-empty notes, and all 13 assets (12 binaries + RPM) plus `sha256sums.txt` resolve on disk.

---------

Co-authored-by: Ben Vincent <neotheo@gmail.com>
Reviewed-on: #18
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

.woodpecker/release.yaml

@@ -113,26 +113,33 @@ steps:
         tea logins add --name gitea --url https://git.unkin.net --token "$${RELEASER_TOKEN}" --no-version-check
         # $$ escapes shell vars/substitutions so Woodpecker doesn't blank them
         # at parse time; ${CI_COMMIT_TAG}/${CI_REPO} are real Woodpecker vars.
-        PREV_TAG=$$(git describe --tags --abbrev=0 HEAD^ 2>/dev/null || echo "")
+        # Find the previous release tag for the changelog range. Several tags can
+        # point at the same commit (e.g. v0.5.3 and v0.5.4), so we skip tags on
+        # the current commit and pick the newest semver tag that is a real
+        # ancestor of this one -- describe HEAD^ would jump too far back.
+        CUR_SHA=$$(git rev-list -n1 "${CI_COMMIT_TAG}")
+        PREV_TAG=""
+        for t in $$(git tag --sort=-v:refname); do
+          [ "$$t" = "${CI_COMMIT_TAG}" ] && continue
+          [ "$$(git rev-list -n1 "$$t")" = "$$CUR_SHA" ] && continue
+          if git merge-base --is-ancestor "$$t" "${CI_COMMIT_TAG}" 2>/dev/null; then
+            PREV_TAG="$$t"; break
+          fi
+        done
         if [ -n "$$PREV_TAG" ]; then
           NOTES=$$(git log "$${PREV_TAG}..${CI_COMMIT_TAG}" --pretty=format:"- %s")
         else
           NOTES=$$(git log --pretty=format:"- %s")
         fi
         tea releases create --tag "${CI_COMMIT_TAG}" --title "${CI_COMMIT_TAG}" --note "$${NOTES}" --login gitea --repo "${CI_REPO}"
-        tea releases assets create "${CI_COMMIT_TAG}" \
-          node-lookup-linux-amd64 \
-          node-lookup-linux-arm64 \
-          node-lookup-darwin-amd64 \
-          node-lookup-darwin-arm64 \
-          pburl-linux-amd64 \
-          pburl-linux-arm64 \
-          pburl-darwin-amd64 \
-          pburl-darwin-arm64 \
-          pblastreport-linux-amd64 \
-          pblastreport-linux-arm64 \
-          pblastreport-darwin-amd64 \
-          pblastreport-darwin-arm64 \
+        # The build step writes the 12 cross-compiled binaries into the workspace
+        # root; the package step writes the RPM to dist/. Generate a checksums
+        # manifest over everything we attach so downloads can be verified.
+        RPM=$$(ls dist/*.rpm 2>/dev/null | head -1)
+        ASSETS="node-lookup-linux-amd64 node-lookup-linux-arm64 node-lookup-darwin-amd64 node-lookup-darwin-arm64 pburl-linux-amd64 pburl-linux-arm64 pburl-darwin-amd64 pburl-darwin-arm64 pblastreport-linux-amd64 pblastreport-linux-arm64 pblastreport-darwin-amd64 pblastreport-darwin-arm64"
+        [ -n "$$RPM" ] && ASSETS="$$ASSETS $$RPM"
+        sha256sum $$ASSETS > sha256sums.txt
+        tea releases assets create "${CI_COMMIT_TAG}" $$ASSETS sha256sums.txt \
           --login gitea --repo "${CI_REPO}"
     depends_on: [upload-rpm]
     backend_options: