feat: initial rpm-changelog composite action

Generates an rpm %changelog entry from git history and prepends it
to the target spec file. Runs in release CI so every tag push gets
a fresh dated entry covering the commits since the previous matching
tag. Avoids stale dates, forgotten bumps, and bogus-weekday warnings.

Inputs: spec path, version, optional release suffix, author,
tag-pattern, exclude-patterns. The last two make the defaults (v*
tags, filter bump-version chores and merges) tweakable for projects
with different conventions.

Migrated from inline logic in helexa/cortex so any project can
adopt the same pattern with a single uses: reference.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

action.yml

@@ -0,0 +1,62 @@
+name: 'Generate RPM %changelog entry'
+description: >
+  Collect commits since the previous release tag and prepend a
+  properly-formatted %changelog entry to an rpm spec file. Keeps
+  the changelog in sync with git history automatically on every
+  release, avoiding stale dates and forgotten bumps.
+author: 'helexa'
+
+branding:
+  icon: file-text
+  color: blue
+
+inputs:
+  spec:
+    description: 'Path to the rpm spec file to update.'
+    required: true
+  version:
+    description: >
+      Version string for the new entry (without release suffix).
+      Typically derived from the git tag, e.g. "0.1.10".
+    required: true
+  release:
+    description: 'Release suffix to append after the version.'
+    required: false
+    default: '1'
+  author:
+    description: >
+      Name and email for the changelog entry, formatted as
+      "Name <email@example.com>".
+    required: false
+    default: 'Gitea Actions <actions@git.lair.cafe>'
+  tag-pattern:
+    description: >
+      Glob pattern for release tags, used to locate the previous
+      release. Default matches the conventional "v*" scheme.
+    required: false
+    default: 'v*'
+  exclude-patterns:
+    description: >
+      Newline-separated list of grep -E patterns (anchored on the
+      bullet "- " prefix) to drop from the generated log. Defaults
+      filter out bump-version bot commits and merge commits.
+    required: false
+    default: |
+      ^- chore: bump version
+      ^- Merge
+
+runs:
+  using: composite
+  steps:
+    - name: Generate changelog entry
+      shell: bash
+      env:
+        SPEC: ${{ inputs.spec }}
+        VERSION: ${{ inputs.version }}
+        RELEASE: ${{ inputs.release }}
+        CHANGELOG_AUTHOR: ${{ inputs.author }}
+        TAG_PATTERN: ${{ inputs.tag-pattern }}
+        EXCLUDE_PATTERNS: ${{ inputs.exclude-patterns }}
+      run: |
+        bash "${{ github.action_path }}/scripts/generate-rpm-changelog.sh" \
+          "$SPEC" "$VERSION"