Sync API

Method	Path	Purpose
`POST`	`/api/v1/sync/pair`	Exchange household key + device id
`GET`	`/api/v1/sync/bundle?since=`	Incremental CRDT / JSON patch bundle
`POST`	`/api/v1/sync/push`	Upload local mutations
`DELETE`	`/api/v1/sync/device/:id`	Unpair old mirror

ℹ️ Note: Conflict resolution is last-write-wins per key unless CRDT mode is enabled in advanced settings.

Troubleshooting

409 version mismatch
Clients on different M2C2 semver — upgrade both mirrors together.