fix(spawn-jdk): make JDK.compareTo consistent with equals

[deer]

JDK.compareTo(JDK) previously ordered instances solely by version(), but equals() also considers operatingSystem, architecture, and home. Two JDKs with the same version but different target platforms therefore compared as equal even though they weren't, which meant storing them in a SortedSet or TreeMap (e.g. a TreeSet<JDK>) would silently drop all but one entry.

The fix introduces a static ORDER comparator on JDK that chains version(), then operatingSystem(), architecture(), and finally home().path() as tie-breakers, and compareTo now delegates to it.