Colored Crosshair - Цветной прицел

Fixes for Minecraft 26.1.x

This release fixes the mod doing nothing at all on Minecraft 26.

• The crosshair is colored again. The mixin config still declared compatibilityLevel: JAVA_21, but the Minecraft 26 build compiles to Java 25 bytecode. Mixin rejected both mixins at load time (Class version 69 required is higher than the class version supported ... (JAVA_21 supports class version 65)) and silently skipped them, so nothing was ever recolored. The compatibility level is now derived from the compile target, so it can't fall out of sync again.
• The Mod Menu settings screen opens again. The Minecraft 26 build shipped a placeholder that just returned the screen you were already on, so the Config button appeared to do nothing. The full settings screen has been ported to the Minecraft 26 GUI API and is wired back up to both the Mod Menu button and /cc settings.

Thanks to the reporter who flagged this on 26.1.2.