feat: add GitHub issue templates (#1655)

* feat: add issue templates for agent requests, bug reports, feature requests, extension submissions, and configuration

* Update .github/ISSUE_TEMPLATE/config.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update .github/ISSUE_TEMPLATE/agent_request.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update .github/ISSUE_TEMPLATE/config.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update .github/ISSUE_TEMPLATE/bug_report.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update .github/ISSUE_TEMPLATE/feature_request.yml

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,17 @@
+blank_issues_enabled: false
+contact_links:
+  - name: 💬 General Discussion
+    url: https://github.com/github/spec-kit/discussions
+    about: Ask questions, share ideas, or discuss Spec-Driven Development
+  - name: 📖 Documentation
+    url: https://github.com/github/spec-kit/blob/main/README.md
+    about: Read the Spec Kit documentation and guides
+  - name: 🛠️ Extension Development Guide
+    url: https://github.com/manfredseee/spec-kit/blob/main/extensions/EXTENSION-DEVELOPMENT-GUIDE.md
+    about: Learn how to develop and publish Spec Kit extensions
+  - name: 🤝 Contributing Guide
+    url: https://github.com/github/spec-kit/blob/main/CONTRIBUTING.md
+    about: Learn how to contribute to Spec Kit
+  - name: 🔒 Security Issues
+    url: https://github.com/github/spec-kit/blob/main/SECURITY.md
+    about: Report security vulnerabilities privately