Add GitHub templates and CI workflow

- PR template
- Issue templates (bug report, feature request)
- Hassfest validation workflow

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,27 @@
+---
+name: Feature Request
+about: Suggest a new feature or enhancement
+title: ''
+labels: enhancement
+assignees: ''
+---
+
+## Feature Description
+
+A clear description of what you would like to see added.
+
+## Use Case
+
+Describe the problem this feature would solve or the use case it enables.
+
+## Proposed Solution
+
+If you have ideas on how to implement this, describe them here.
+
+## Alternatives Considered
+
+Any alternative solutions or features you've considered.
+
+## Additional Context
+
+Any other context, screenshots, or examples.