feat(conditions): add conditions engine DB schema and evaluation API
- Four tables: conditions, conditions_groups, conditions_rules, conditions_map
- ConditionsHelper with pass(), load(), shouldDisplay(), getConditionsForItem()
- 7 rule types: menu_item, home_page, user_group, access_level, date, day, url
- Hierarchical evaluation: condition → groups (AND/OR) → rules (AND/OR)
- Runtime cache for repeated evaluations within same request
- Foundation for Advanced Module Manager (#160) and Conditional Content (#164)
Jonathan Miller
ae6719049d