Port to Minecraft 26.1.2

[Sukikui]

• Update Minecraft, Fabric Loader, Fabric API, Mod Menu and Cloth Config versions for 26.1.2
• Switch from Yarn mappings to Mojang official mappings required by Minecraft 26.1+
• Update Gradle/Loom configuration and Java target to Java 25
• Migrate client code to the new Mojang/Fabric API class and method names
• Adapt the config screen rendering and widgets to the 26.1 GUI API
• Keep numeric filtering behavior for API and origin port fields after the EditBox API change
• Update mod metadata and README to reflect Minecraft 26.1.2 / Java 25 support