Add Kiro IDE support (.kiro/) (#548)

Co-authored-by: Sungmin Hong <hsungmin@amazon.com>

.kiro/steering/dev-mode.md

@@ -0,0 +1,44 @@
+---
+inclusion: manual
+description: Development mode context for active feature implementation and coding work
+---
+
+# Development Mode
+
+Use this context when actively implementing features or writing code.
+
+## Focus Areas
+
+- Write clean, maintainable code
+- Follow TDD workflow when appropriate
+- Implement incrementally with frequent testing
+- Consider edge cases and error handling
+- Document complex logic inline
+
+## Workflow
+
+1. Understand requirements thoroughly
+2. Plan implementation approach
+3. Write tests first (when using TDD)
+4. Implement minimal working solution
+5. Refactor for clarity and maintainability
+6. Verify all tests pass
+
+## Code Quality
+
+- Prioritize readability over cleverness
+- Keep functions small and focused
+- Use meaningful variable and function names
+- Add comments for non-obvious logic
+- Follow project coding standards
+
+## Testing
+
+- Write unit tests for business logic
+- Test edge cases and error conditions
+- Ensure tests are fast and reliable
+- Use descriptive test names
+
+## Invocation
+
+Use `#dev-mode` to activate this context when starting development work.