docs: Update coverage threshold documentation in CONTRIBUTING.md

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

CONTRIBUTING.md

@@ -182,7 +182,8 @@ describe('MyComponent', () => {
 - Write tests for all new features
 - Test user interactions, not implementation details
 - Use meaningful test descriptions
-- Aim for 80%+ code coverage
+- Maintain or improve code coverage (current thresholds: 60% lines, 40% functions, 35% branches, 60% statements)
+- Aim to gradually increase coverage toward the long-term goal of 80%+ across all metrics
 - Test edge cases and error states
 
 ## Code Style
@@ -373,6 +374,16 @@ Our repository includes several automated GitHub workflows that will run when yo
 - **Tests**: Runs unit and integration tests
 - **Build**: Ensures all packages build successfully
 - **Matrix Testing**: Tests on Node.js 18.x and 20.x
+- **Coverage Thresholds**: Enforces minimum test coverage (see below)
+
+##### Test Coverage Requirements
+The project enforces minimum test coverage thresholds to maintain code quality:
+- **Lines**: 60% (target: gradually increase to 80%)
+- **Functions**: 40% (target: gradually increase to 80%)
+- **Branches**: 35% (target: gradually increase to 75%)
+- **Statements**: 60% (target: gradually increase to 80%)
+
+These thresholds are intentionally set below our long-term goals to prevent CI failures while we improve test coverage. New code should aim for higher coverage than these minimums.
 
 #### Security Scans
 - **CodeQL**: Scans for security vulnerabilities in code