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

pom.xml

@@ -20,7 +20,7 @@
     </modules>
 
     <properties>
-        <maven.compiler.release>27</maven.compiler.release>
+        <maven.compiler.release>25</maven.compiler.release>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 
         <spring-boot.version>4.1.1</spring-boot.version>
@@ -119,7 +119,7 @@
                         <configuration>
                             <rules>
                                 <requireJavaVersion>
-                                    <version>[27,)</version>
+                                    <version>[25,)</version>
                                 </requireJavaVersion>
                             </rules>
                         </configuration>