minecraft-server: move to the java25 line (4.1.0+up2026.8.2.java25)

Minecraft 26.2 requires Java 25, so the chart's default minecraft.version can
only be raised on a java25 image. appVersion becomes 2026.8.2-java25 - the same
dated upstream release the java21 line ships, so the only variables that change
are the JVM and the Minecraft version.

The chart version stays at 4.1.0: the Java lines are siblings of one chart
generation, not successors, and are told apart by the +up suffix.

The Java boundaries in the values.yaml / NOTES.txt comments are read off
Mojang's version manifest (javaVersion.majorVersion per release), not
estimated: 1.21.11 is the last release asking for Java 21, every release from
26.1 on asks for Java 25.

minecraft-server/templates/NOTES.txt

@@ -81,11 +81,13 @@ THIS CHART IS PUBLISHED ONCE PER JAVA LINE — THIS IS {{ $line | default "an un
   ({{ .Chart.AppVersion }}), not from a value. This build runs
   minecraft.version {{ .Values.minecraft.version }}.
 
-  Java 8 runs Minecraft up to 1.16.5, 1.18-1.20.4 need Java 17 and 1.20.5+ need
-  Java 21. Nothing in this chart checks that minecraft.version fits the line:
-  a mismatch renders and installs without a word, and only the container fails
-  afterwards — CrashLoopBackOff once the startup budget{{ if $budget }} ({{ $budget }}){{ end }} is spent, with
-  the reason in the log and nowhere else:
+  Java 8 runs Minecraft up to 1.16.5, 1.18-1.20.4 need Java 17, 1.20.5-1.21.11
+  need Java 21 and 26.1 and later need Java 25 (read off Mojang's version
+  manifest, javaVersion.majorVersion per release). Nothing in this chart checks
+  that minecraft.version fits the line: a mismatch renders and installs without
+  a word, and only the container fails afterwards — CrashLoopBackOff once the
+  startup budget{{ if $budget }} ({{ $budget }}){{ end }} is spent, with the reason in the log and
+  nowhere else:
 
     kubectl -n {{ .Release.Namespace }} logs {{ $pod }}