add changeset for test improvements, fixes, and code quality

Author: gorango

.changeset/test-improvements-and-fixes.md

@@ -0,0 +1,20 @@
+---
+"flowcraft": patch
+---
+
+**Test Suite Enhancements:**
+- Comprehensive test coverage improvements across runtime, evaluators, and flow components
+- Added fuzz testing and security boundary validation
+- Enhanced performance and resource testing capabilities
+- Cross-environment compatibility testing
+- End-to-end integration test scenarios
+
+**Runtime Fixes:**
+- Enhanced runtime with configurable scheduler and circular reference handling
+- Added null safety checks in runtime components
+- Prevented prototype pollution in blueprint sanitizer
+- Fixed infinite loop prevention with negative concurrency values
+
+**Code Quality:**
+- Improved test coverage thresholds and enforcement
+- Better error handling and validation throughout the codebase