[ENG-1849] Persist Roam node type schema labels (#1131)

* [ENG-1847] Define shared cross-app node content contract

* [ENG-1849] Add node-type schema dependency to cross-app node fixtures

The cross-app node contract (ENG-1847) carries nodeType = { sourceLocalId, label } and the instance Concept references it via schema_represented_by_local_id, but the fixtures persisted no is_schema:true schema Concept for that id. Add the required schemaConcept (Roam Claim, Obsidian Evidence) carrying stable source identity + label only -- no source_data/format/color/tag, per the contract's "without redefining schema shape".

Roam's existing 5-min sync already persists the schema Concept per contract (convertDgToSupabaseConcepts -> discourseNodeSchemaToLocalConcept; all types on initial sync, edited types incrementally via nodeTypeSince), so no Roam sync code change is needed for F4/F9/F13. Stacked on eng-1847 (PR #1129, unmerged).

* [ENG-1849] Persist Roam schema labels

Author: sid597

apps/roam/src/utils/conceptConversion.ts

@@ -78,17 +78,21 @@ export const discourseNodeSchemaToLocalConcept = (
   node: DiscourseNode,
 ): LocalConceptDataInput => {
   const titleParts = node.text.split("/");
+  const label = titleParts[titleParts.length - 1] ?? node.text;
   const result: LocalConceptDataInput = {
     space_id: context.spaceId,
     name: node.text,
     source_local_id: node.type,
     is_schema: true,
+    literal_content: {
+      label,
+    },
     /* eslint-enable @typescript-eslint/naming-convention */
     ...getNodeExtraData(node.type),
   };
   if (node.template !== undefined)
     result.literal_content = {
-      label: titleParts[titleParts.length - 1],
+      label,
       template: templateToText(node.template),
     };
   return result;