Adds lesson_plans_router.py with 10 endpoints under /lessons/plans:
GET/POST /plans, GET/PATCH/DELETE /plans/{id}, POST /plans/{id}/deliver,
GET /plans/{id}/deliveries, POST/DELETE /plans/{id}/collaborators,
POST /plans/{id}/suggest (Ollama-backed per-field AI suggestions).
objectives and activities stored as JSONB arrays with Bloom taxonomy support.
Registers router in run/routers.py. Adds seed_test_environment.py for
platform-admin triggered reset + seed of demo users and Neo4j.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
