- **Introduce Variable System**
- Added singleton class for variable management
- Implemented script commands `[var]` and `[add]` for variable control
- Supported variable substitution (`{variable}`) in dialogue and choices
- **Expand Script Features**
- Added `[scene]` command for scene transition (load scene and link next script)
- **Improve Character Presentation**
- Refactored character object hierarchy for better animation control
- Applied mask-based soft transition effect (Soft Wipe) for expression changes
- Separate character hierarchy into Slot → MotionContainer → Image
- Improve expression change with mask-based smooth transition
- Replace scene-based navigation with label-based jump system
- Add Top direction support and refactor direction vector logic
- Minor code improvements (C# index operator, cleaner initialization)
