get_global_driver() now sets _driver_unavailable=True when the initial
connection fails, so subsequent calls fail immediately instead of
spending 60s retrying each time. Added reset_global_driver() to allow
manual reconnection after Neo4j comes back up.
Also fixes APP_BOLT_URL in .env: was bolt://bolt.classroomcopilot.ai
(public IP, port not exposed), now bolt://192.168.0.209:7687 (LAN).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
