fix: Implement --version flag output in JabKit CLI (#14431)

Previously, running `jabkit --version` produced no output.

This fix adds logic in the run() method to check if the
versionInfoRequested flag is set. When true, it outputs
just the version string (e.g., "6.0-alpha.197--2025-11-24--0a9793a")
and returns early.

Fixes #14428

Author: manojalluri

jabkit/src/main/java/org/jabref/toolkit/commands/JabKit.java

@@ -77,6 +77,10 @@ public JabKit(CliPreferences cliPreferences, BibEntryTypesManager entryTypesMana
 
     @Override
     public void run() {
+        if (versionInfoRequested) {
+            System.out.println(new BuildInfo().version);
+            return;
+        }
         System.out.printf(BuildInfo.JABREF_BANNER + "%n", new BuildInfo().version);
     }