Bring neo4j-schema-init.py in line with the v2.4.0 schema doc: add Solution
and Demo node types (constraints + name/status indexes), 79 -> 81 node types,
update test guards and the dry-run constant. Quentin's Solution/Demo writes
now get id-uniqueness constraints instead of allowing duplicates.
Correct aws_sa's scope framing: it has no host or environment, so a demo-only
boundary on it asserted access it doesn't have. Remove the demo-only claim from
aws-sa.md (keep the subagent-relationship framing); soften quentin.md so the
demo boundary is owned by Quentin (his Ergon host), not a property of aws_sa.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>