Java 26.3 data: optional sign text filtered messages

Built from the tested support/java-26.3 wrapper (518e467) and its pinned data submodule (minecraft-data 38fbd69). Adds to data-10: the filtered messages of 26.3 sign_text_front and sign_text_back item components are optional (SignText.STREAM_CODEC uses ByteBufCodecs.optional), so container contents with a sign item, as Spigot 26.3 sends them, parse again. No other data changed.

SHA-256: daf7c3b36b14dfb9cfd0ffa6aaa8b000e0c85e37c36decc90674ec158fab8d02
npm integrity: sha512-SWgwkto2vD1cqpmTShT31y3ko3rbPMRwEEIXkQ0F8RNJrHNvKESyhMK6MmMLU9uPt3hJh2tIxoRBqyFVneYsWg==