chore: add community health files

Add MIT LICENSE (root, backend, frontend), CONTRIBUTING.md, CODE_OF_CONDUCT.md,
SECURITY.md, GitHub issue templates (bug/feature), and PR template.

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

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,22 @@
+---
+name: Feature request
+about: Suggest an idea or improvement for temetro
+labels: enhancement
+---
+
+**Is your feature request related to a problem?**
+A clear description of the problem. e.g. "I'm frustrated when..."
+
+**Describe the solution you'd like**
+A clear description of what you want to happen.
+
+**Which part of the project does this affect?**
+- [ ] Frontend (Next.js chat UI)
+- [ ] Backend (API / auth / database)
+- [ ] Both
+
+**Alternatives considered**
+Any alternative solutions or features you've considered.
+
+**Additional context**
+Any other context, mockups, or screenshots.