Starting with 26.1 Mojang ships Minecraft unobfuscated, and Yarn /
Intermediary are no longer published past 1.21.11. Loom does not need
a mappings dependency in that mode: the Mojang-named source compiles
directly. Remove the mappings line, drop the yarn_mappings property,
revert the client entrypoint to Mojang names (Minecraft, Component,
ChatFormatting, gui.getChat(), getUser().getName()), and rewrite the
README note so it stops claiming Mojang mappings via Loom.
