[harshkumawat5]

Summary

• Route forced single-quoted and literal scalars containing non-printable bytes or a UTF-8 BOM through the existing escaped double-quoted style.
• Add round-trip regression coverage for NUL, U+0001, and BOM values in both forced styles.

Root cause

The forced-style validators did not reject non-printable input, so the emitter wrote bytes that those YAML scalar styles cannot represent safely.

Testing

• All four new regression cases failed before the fix and pass with it.
• Full CTest suite passes: 3/3 test targets (1,072 unit tests; 8 disabled).
• Formatting and whitespace checks pass. The strict C++11 build succeeds; pre-existing header shadow warnings and a duplicate-library linker warning remain.

Not included

No broader emitter refactoring.