Push character template changes down to existing characters

when a world’s character sheet template changes (new attributes added, mechanics tweaked), existing characters don’t retroactively pick up the diff. They were seeded at creation, then frozen. For mature systems this is correct (version-controlled stability). But we need a path to opt-in push: either a “Sync characters with template” action on the world edit page (adds missing attributes to all characters, doesn’t overwrite or delete existing), or versioned templates where each character records which template version they were seeded from. Useful once a DM has locked a system and wants to evolve it deliberately.