- Create aisbf/database.py with DatabaseManager class
- Track context dimensions (context_size, condense_context, condense_method, effective_context)
- Track token usage for rate limiting (TPM, TPH, TPD)
- Auto-create database at ~/.aisbf/aisbf.db if it doesn't exist
- Clean up old token usage records to prevent database bloat
- Export database module in __init__.py
- Update setup.py to include database.py in package data