feat(workflow): Gitea-Wiki als generierter Spiegel von docs/ (#192)

Konverter .gitea/scripts/wiki_mirror.py, Push-Skript wiki-push.sh, Job wiki-mirror in release.yml, Dispatch-Workflow wiki-mirror.yml und --check-Schritt in ci.yml. Version 9.0.0-beta.13.

Files changed:
- .gitea/scripts/wiki-push.sh
- .gitea/scripts/wiki_mirror.py
- .gitea/workflows/ci.yml
- .gitea/workflows/release.yml
- .gitea/workflows/wiki-mirror.yml
- CHANGES.md
- README.md
- VERSION
- docs/dev/development.md
- tools/chemenu/tests/test_wiki_mirror.py

Co-Authored-By: Claude Code <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

.gitea/workflows/ci.yml

@@ -194,6 +194,14 @@ jobs:
           tools/wikitool instructions verify
           tools/wikitool lint --fail-on-error
 
+      - name: Wiki mirror converts the docs
+        # The Gitea wiki mirrors docs/ at every release (release.yml, job wiki-mirror). A link the
+        # converter cannot resolve, or two pages that would share a wiki name, is cheaper to hear
+        # about here than when the release is cut. Writes nothing.
+        run: |
+          set -eu
+          python3 .gitea/scripts/wiki_mirror.py --check --source . --version "$(tr -d '[:space:]' < VERSION)"
+
       - name: Version gate
         # A stack change with no version bump cannot be released, because the
         # release would carry a change nobody named. Scoped to what