On Windows the expert enable-status check compared `fs::read_link` output
against the central path, which silently failed for junctions: the link
state fell back to Broken/LinkedElsewhere, so enabled experts kept
reappearing as disabled and disappeared from the message-input expert
list. Switch the link verification to canonicalize both sides (which
transparently follows junctions and symlinks) and add a case-insensitive
path comparison on Windows. Also prefer `junction::get_target` for the
displayed target path.
b79f06f7ae