Fix syncframeworks main CI gates

[davidahmann]

Summary

• harden the syncframeworks generator file access to satisfy gosec
• add direct tests for the generator package and cover the main/fail code paths
• keep the framework sync behavior unchanged while restoring main CI coverage

Validation

• go test ./...
• ./scripts/check_go_package_coverage.py coverage.out 85 github.com/Clyra-AI/proof/core/exitcode,github.com/Clyra-AI/proof/internal/testutil
• make lint