Fix hookify enabled boolean parsing

[parasol-aser]

Summary

• parse Hookify enabled frontmatter as a strict boolean
• accept common YAML boolean spellings: true/false, yes/no, on/off, and 1/0
• reject invalid enabled values instead of letting truthy strings activate rules
• add focused unittest coverage for boolean spellings and disabled-rule loading

Fixes #57107.

Tests

python3 -B -m unittest discover -s plugins/hookify/tests

PYTHONPATH=plugins python3 -B - <<'PY'
from hookify.core.config_loader import extract_frontmatter, Rule
fm, msg = extract_frontmatter("---\nname: r\nenabled: no\nevent: bash\npattern: rm -rf\n---\nmsg\n")
r = Rule.from_dict(fm, msg)
print(repr(fm["enabled"]), bool(r.enabled))
PY

The reproduction now prints False False.