Feature Request: Add support for Minecraft 1.21.x

### Feature Request I would like to suggest adding long-term support for **Minecraft 1.21.1 / NeoForge 21.1.x** in Hydraulic, instead of only targeting the latest 1.21.11 version. ### Reasoning 1. **Stable Hybrid Ecosystem:** Many mature hybrid servers like **Arclight** are still based on Minecraft 1.21.1 as their core stable version and have not yet migrated to 1.21.11. This creates a dependency conflict when using the latest Hydraulic builds. 2. **Mod Compatibility:** Many popular content mods only have stable releases for Minecraft 1.21.1. Upgrading to 1.21.11 forces users to abandon these core gameplay mods. 3. **Lower Deployment Barrier:** Supporting the widely adopted 1.21.1 version allows users to leverage their existing, stable server environments, significantly reducing the cost and risk of deploying Hydraulic