Add OCI image labels, issue template config, paths-ignore, and metadata fixes

- Dockerfile: ARG VERSION + OCI labels (title, description, source, licenses, version)
- release.yml: pass VERSION build-arg to all four image builds
- docker-publish.yml: extend paths-ignore to cover community files
- .github/ISSUE_TEMPLATE/config.yml: disable blank issues, link to Discussions and wiki
- README.md: add Getting Help section
- pyproject.toml: expand description; add System Administrators audience classifier

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Question or help request
+    url: https://github.com/sudolulo/winnow/discussions
+    about: Ask questions and get help in GitHub Discussions
+  - name: Wiki / Documentation
+    url: https://github.com/sudolulo/winnow/wiki
+    about: Setup, troubleshooting, and FAQ