fix: store raw API schema in forked_from to avoid double transformation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/lib/components/DatatableSchemaDiff.svelte

@@ -1,7 +1,6 @@
 <script module lang="ts">
 	import {
 		type TableEditorValues,
-		type TableEditorValuesColumn,
 		type TableEditorForeignKey,
 		columnDefToTableEditorValuesColumn
 	} from '$lib/components/apps/components/display/dbtable/tableEditor'
@@ -321,12 +320,17 @@
 			return
 		}
 
-		// Update forked_from.schema for the migrated table
+		// Update forked_from.schema for the migrated table using raw API format
 		try {
-			const sourceSchema =
-				drawerDirection === 'ahead' ? drawerDiff.forkSchema : drawerDiff.parentSchema
+			const targetWorkspace = drawerDirection === 'ahead' ? parentWorkspaceId : currentWorkspaceId
 			const { schemaName, tableName } = drawerChange
-			const newTableDef = sourceSchema[schemaName]?.[tableName]
+
+			// Re-fetch the raw schema from the target (post-migration) to store as new baseline
+			const rawSchema = await WorkspaceService.getDatatableFullSchema({
+				workspace: targetWorkspace,
+				requestBody: { source: `datatable://${dtName}` }
+			})
+			const newTableDef = rawSchema[schemaName]?.[tableName]
 
 			const forkSettings = await WorkspaceService.getSettings({
 				workspace: currentWorkspaceId