Fixed

• JitPack build compatibility - corrected jitpack.yml Java selector to openjdk21 and pinned JitPack install to ./mvnw -B -ntp -DskipTests install so builds consistently use Java 21 when compiling against paper-api 1.21.11.
• GitHub Actions version drift - updated workflow actions to current major versions across CI/release publishing (actions/checkout@v6, actions/setup-java@v5, actions/cache@v5, actions/upload-artifact@v7).
• Paper/Folia smoke test resolution for 26.x - CI smoke jobs now resolve builds from fill.papermc.io/v3 and correctly include MC 26.1 with Java 25 where required.

Changed

• Modrinth release step - replaced the legacy Kir-Antipov/mc-publish action invocation in release workflow with a direct Modrinth v2 API upload path for clearer failure diagnostics and up-to-date version resolution.