Add db_url property to MemoriManager that falls back to
CHECKPOINT_DB_URL setting, and pass it explicitly from
fastapi_app.py to ensure Memori can create sync connections.
This fixes the error "Either db_pool or db_url must be provided"
when recalling memories.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>