Target JDK 25 LTS instead of JDK 27

maven.compiler.release and the enforcer floor go to 25, and both the
GitHub CI and the Gitea publish workflow use Temurin 25.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G71TQ5jDETVwdUJxGAwaiT

.gitea/workflows/publish.yml

@@ -36,7 +36,7 @@ jobs:
       - uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: '27'
+          java-version: '25'
           cache: maven
           # writes ~/.m2/settings.xml with a <server id="gitea"> reading these env vars
           server-id: gitea