docs: remove test coverage metrics from implementation docs

Author: hiddentao

.devdocs/implementation.md

@@ -271,10 +271,7 @@ Error
 
 ### Test Coverage
 
-**Current Metrics:**
-- Line Coverage: 97.00%
-- Function Coverage: 93.09%
-- Branch Coverage: >90%
+The project maintains comprehensive test coverage across all modules with high coverage metrics for both unit and integration tests.
 
 ### Test Structure