feat: add prepare and publish composite actions

Add two focused subdirectory composite actions:

- prepare/action.yml: downloads the vociferate binary, runs it to update
  changelog and release-version, then commits, tags, and pushes — replacing
  the boilerplate git steps consumers previously had to write inline.

- publish/action.yml: extracts the matching changelog section and creates or
  updates the Gitea/GitHub release. Outputs release-id, tag, and version so
  consumers can upload their own assets after it runs.

Simplify the vociferate workflows to use ./prepare and ./publish directly,
validating both actions in the self-release pipeline.

Update README to show the clean two-action usage pattern.

.gitea/workflows/prepare-release.yml

@@ -21,8 +21,6 @@ jobs:
     defaults:
       run:
         shell: bash
-    env:
-      RELEASE_TOKEN: ${{ secrets.GITHUB_TOKEN }}
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -37,91 +35,20 @@ jobs:
           cache: true
           cache-dependency-path: go.sum
 
-      - name: Resolve release version
-        id: resolve-version
-        env:
-          INPUT_VERSION: ${{ inputs.version }}
-        run: |
-          set -euo pipefail
-
-          provided_version="$(printf '%s' "${INPUT_VERSION:-}" | sed 's/^[[:space:]]\+//; s/[[:space:]]\+$//')"
-
-          if [[ -n "$provided_version" ]]; then
-            release_version="$provided_version"
-          else
-            if ! release_version="$(go run ./cmd/vociferate --recommend --root . 2>release-recommendation.err)"; then
-              recommendation_error="$(tr '\n' ' ' < release-recommendation.err | sed 's/[[:space:]]\+/ /g' | sed 's/^ //; s/ $//')"
-              echo "Resolve release version: ${recommendation_error}" >&2
-              exit 1
-            fi
-          fi
-
-          echo "RELEASE_VERSION=$release_version" >> "$GITHUB_ENV"
-          echo "version=$release_version" >> "$GITHUB_OUTPUT"
-
-      - name: Prepare release files
-        run: |
-          set -euo pipefail
-          go run ./cmd/vociferate \
-            --root . \
-            --version "$RELEASE_VERSION" \
-            --date "$(date -u +%F)" \
-            --changelog changelog.md
-
       - name: Run tests
-        run: |
-          set -euo pipefail
-          go test ./...
+        run: go test ./...
 
-      - name: Configure git author
-        run: |
-          set -euo pipefail
-          git config user.name "gitea-actions[bot]"
-          git config user.email "gitea-actions[bot]@users.noreply.local"
-
-      - name: Commit release changes and push tag
-        run: |
-          set -euo pipefail
-
-          normalized_version="${RELEASE_VERSION#v}"
-          tag="v${normalized_version}"
-
-          if git rev-parse "$tag" >/dev/null 2>&1; then
-            echo "Tag ${tag} already exists" >&2
-            exit 1
-          fi
-
-          case "$GITHUB_SERVER_URL" in
-            https://*)
-              authed_remote="https://oauth2:${RELEASE_TOKEN}@${GITHUB_SERVER_URL#https://}/${GITHUB_REPOSITORY}.git"
-              ;;
-            http://*)
-              authed_remote="http://oauth2:${RELEASE_TOKEN}@${GITHUB_SERVER_URL#http://}/${GITHUB_REPOSITORY}.git"
-              ;;
-            *)
-              echo "Unsupported GITHUB_SERVER_URL: ${GITHUB_SERVER_URL}" >&2
-              exit 1
-              ;;
-          esac
-
-          git remote set-url origin "$authed_remote"
-          git add changelog.md release-version
-          git commit -m "release: prepare ${tag}"
-          git tag "$tag"
-          git push origin HEAD
-          git push origin "$tag"
+      - name: Prepare and tag release
+        id: prepare
+        uses: ./prepare
+        with:
+          version: ${{ inputs.version }}
+          token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Summarize prepared release
         run: |
           set -euo pipefail
-
-          normalized_version="${RELEASE_VERSION#v}"
-          tag="v${normalized_version}"
-
+          tag="${{ steps.prepare.outputs.version }}"
           {
             echo "## Release Prepared"
             echo
-            echo "- Updated files were committed to main."
-            echo "- Tag pushed: ${tag}"
-            echo "- The tag-triggered Do Release workflow will create or update the release and publish binaries."
-          } >> "$GITHUB_STEP_SUMMARY"