feat: Add task scheduler system, multiple admins support, GPT-5 integration

- Add complete task scheduling system with CRUD operations
- Support for once/daily/interval task types
- Multiple admins support throughout the system
- GPT-5 integration for Deep Agent with reasoning capabilities
- New AI tools for task management (create, update, delete, list)
- Improved localization with task scheduler messages
- Fixed credit allocation logic for admins
- Enhanced user experience with structured capability descriptions
- Added performance optimizations for MCP servers