Final Plan Summary - Build Fix Implementation (5.5 hours)

1. Audit Transform Pipeline (1.5h): Check for lambdas/pattern matching, remove only error_prop duplicates, preserve working features

2. Implement Automatic Import Detection (2h): Add ImportTracker to preprocessor, detect standard library function calls, inject imports using astutil

3. Fix Source Mappings (1h): Adjust mapping offsets for added imports, verify accuracy with dedicated tests

4. Verify & Document (1h): Build all packages, compile 46 golden tests, update CHANGELOG.md and architecture docs
