solo gates mod

## v0.2.0 — Initial Release

### Added
- Rank system with 5 tiers: E, C, B, A, S
- S+ boss gates with special encounters
- Custom Dungeon dimension (flat Deep Dark arena)
- Gate collapse mechanic — mobs invade Overworld on failure
- 5 rank-based armor sets with custom textures
- 4-tier currency system: Bronze, Silver, Gold, Platinum
- 11 custom advancements
- Billboard portal rendering with animated layers
- Full server config (mob lists, rewards, spawn rates, cooldowns)
- Multiplayer support — instanced gates per player
- English and French translations