fix(vulndb): disable retired OSV JSONL default

[9batalion]

Summary

• disables the retired OSV JSONL endpoint in the generated vuln-db init-config output
• records the current OSV full dump all.zip location as adapter-required instead of auto-enabled
• bumps hotfix version to 3.1.2

Verification

• python3 -m pytest tests/test_default_update_config.py tests/test_full_update_pipeline.py tests/test_osv_full_feed.py -q
• PYTHONPATH=. python3 -m src --version
• python3 -m build --sdist --wheel
• installed built wheel in clean venv and verified secret-scanner 3.1.2 plus vuln-db init-config OSV disabled/current URL

Boundary

This does not claim full OSV/CVE import support. It prevents the default full-update config from failing on the retired 404 OSV JSONL URL.