chore(ci): improve repository maintenance configuration

- Enable weekly Dependabot updates for GitHub Actions dependencies
- Consolidate duplicate Trivy scans into a single SARIF scan with exit-code gate
- Ignore macOS metadata and locally downloaded drone-ssh binaries
- Add feature request issue template and pull request checklist template

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,36 @@
+---
+name: Feature request
+about: Suggest an idea for this action
+title: ""
+labels: enhancement
+assignees: appleboy
+---
+
+## Is your feature request related to a problem?
+
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+## Describe the solution you'd like
+
+A clear and concise description of what you want to happen.
+
+## Example Yaml Config
+
+If applicable, show how you would expect to use the new feature:
+
+```yaml
+- name: executing remote ssh commands
+  uses: appleboy/ssh-action@v1
+  with:
+    host: ${{ secrets.HOST }}
+    username: ${{ secrets.USERNAME }}
+    key: ${{ secrets.KEY }}
+    script: whoami
+```
+
+## Additional context
+
+Add any other context about the feature request here. Note that SSH connection
+behavior (ciphers, timeouts, proxy, etc.) is implemented in
+[drone-ssh](https://github.com/appleboy/drone-ssh) - feature requests for
+connection behavior may belong there.