Add WikilinkNode and DatabaseView schema-only nodes to @docmost/editor-ext
and register them in the Hocuspocus server tiptapExtensions list.
Without the shared schema, jsonToNode on the server hit a RangeError for
those node types and stripUnknownNodes dropped them on every collab save,
so wikilinks disappeared on page reload and database-view embeds lost
their config and rendered as empty placeholders.
