feat: give plugins their own tables, migrations and sync entities

electron/remote-sync-entities.cjs

@@ -1,3 +1,8 @@
+// The fallback list, for a server older than GET /sync/entity-types.
+//
+// Current servers return the entity types and their order, which is the only
+// way this process learns about one a plugin added. This array is what those
+// servers would have synced anyway, so an old pairing keeps working.
 const SYNCED_ENTITY_TYPES = Object.freeze([
   // Ordered by reference dependency: hosts and snippets resolve credential,
   // vault and folder syncIds, so those have to exist on the other side first.