verify_seed_data.py hardcoded EXPECTED_SEED_VERSION = "local-dev-demo-v3"
but seed_demo_data.py was bumped to v4 in the preview PR, so the
post-seed verifier would falsely fail with a version mismatch. Extract
the constant to scripts/dev/seed_shared.py and import it from both
sides so the two scripts always agree.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
