Run ruff check --fix: remove unused imports (F401), fix f-strings
without placeholders (F541), remove unused variables (F841), fix
duplicate dict key (F601).
Run isort --profile black: normalize import ordering across all files.
Run ruff format: apply consistent formatting (black-compatible) to
all 58 Python files.
3 intentional E402 remain (imports after require_yaml() must execute
after yaml is available).
replace yaml.dump with surgical text edits for contents/source_ref.
preserves comments, block scalars, quoting, indentation.
fix FBNeo new entry detection using parsed keys instead of text search.
sparse clone upstream repos, parse BIOS root sets from C source,
cache as JSON, merge into emulator profiles with backup.
covers macro expansion, version detection, subset profile protection.
