Add comprehensive issue templates for improved triage

This commit implements Phase 4 goals from the Daily Backlog Burner roadmap
by adding structured issue templates to improve issue triage and quality.

Added templates:
- Bug Report: Comprehensive template for crash/correctness issues
- Performance Issue: Specialized template for performance problems
- Feature Request: Structured template for enhancement requests
- Question: Template that guides users to appropriate channels
- Build/Installation: Template for compilation and setup issues
- Other: Catch-all template for miscellaneous issues
- Config: Directs users to external resources (Discussions, Stack Overflow)

Benefits:
- Improves issue quality through structured reporting
- Reduces maintainer time spent asking for missing information
- Guides users to appropriate channels (Discussions vs Issues)
- Enables better categorization and prioritization
- Addresses identified patterns from backlog analysis

These templates directly support the backlog management goals identified
in issue #7903, helping transform the issue process from reactive to
well-organized community engagement.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,17 @@
+blank_issues_enabled: false
+contact_links:
+  - name: 💬 GitHub Discussions
+    url: https://github.com/Z3Prover/z3/discussions
+    about: For general questions, usage help, and community discussions
+  - name: 📚 Stack Overflow
+    url: https://stackoverflow.com/questions/tagged/z3
+    about: For specific programming questions and code examples with Z3 APIs
+  - name: 📖 Z3 Guide
+    url: https://microsoft.github.io/z3guide/
+    about: Comprehensive tutorials and documentation for learning Z3
+  - name: 📝 API Documentation
+    url: https://z3prover.github.io/api/html/index.html
+    about: Complete API reference for all Z3 language bindings
+  - name: 🔬 Z3 Theory and Research
+    url: https://theory.stanford.edu/~nikolaj/programmingz3.html
+    about: Academic resources and theory behind Z3's algorithms