Unseen

Three fixes, backed by a new runtime test suite (75 assertions on Paper 1.21.11 and 26.2):

• Unvanish no longer clears state owned by other plugins (god mode, sleeping-ignored) - Unseen only reverts what it set itself.
• Mobs that were already targeting you are released on vanish (cancelling EntityTargetEvent only stops new targeting).
• Disabling the plugin now restores hidden players and invulnerability instead of leaving an invisible, immortal staff member behind.
• Legacy & colour codes are kept when the text also contains <...> decoration.
• The jar reports its real version in /plugins.