ci: auto-generate rpm changelog entry per release

On every tag push, build a %changelog entry from the git log since
the previous v* tag and prepend it to each spec. Stops the initial
entry from drifting further and catches bogus-date / stale-version
warnings automatically since the generated date always matches the
day the CI runs.

The generator drops "chore: bump version" commits (bot-authored,
noisy in user-facing changelogs) and merge commits. Author defaults
to the gitea-actions identity but can be overridden via
CHANGELOG_AUTHOR env var if a human release is desired.

Requires fetch-depth: 0 on checkout so git describe can see prior
tags and git log can reach them.

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

.gitea/workflows/ci.yml

@@ -66,6 +66,8 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/v')
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: Determine version
         id: version
@@ -79,6 +81,9 @@ jobs:
           sed -i '/\[workspace\.package\]/,/\[/{ s/^version = ".*"/version = "'"${VERSION}"'"/ }' Cargo.toml
           sed -i "s/^Version:.*/Version:        ${VERSION}/" cortex.spec
 
+      - name: Generate changelog entry
+        run: bash .gitea/scripts/generate-rpm-changelog.sh cortex.spec "${{ steps.version.outputs.VERSION }}"
+
       - name: Generate source tarball
         run: |
           set -ex
@@ -118,6 +123,8 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/v')
     steps:
       - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
 
       - name: Determine version
         id: version
@@ -131,6 +138,9 @@ jobs:
           sed -i '/\[workspace\.package\]/,/\[/{ s/^version = ".*"/version = "'"${VERSION}"'"/ }' Cargo.toml
           sed -i "s/^Version:.*/Version:        ${VERSION}/" neuron.spec
 
+      - name: Generate changelog entry
+        run: bash .gitea/scripts/generate-rpm-changelog.sh neuron.spec "${{ steps.version.outputs.VERSION }}"
+
       - name: Generate source tarball
         run: |
           set -ex