Restore java platform URLs in mise.lock

A prior mise.lock regeneration replaced java's per-platform url and
checksum entries with a bare [tools.java.options] shorthand_vendor.
Without locked URLs, 'mise install --locked' fails with 'No lockfile
URL found for java@26.0.1', which broke the gh-pages deploy (it runs
the full locked install). Restore the per-platform entries.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: oschwald