fix(knowledge): make EMBEDDING_DIMENSIONS a literal type

CreateKnowledgeBaseData.embeddingDimension is typed as the literal 1536,
so EMBEDDING_DIMENSIONS needs `as const` to satisfy it after the copilot
path switched to passing the constant.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/lib/knowledge/embedding-models.ts

@@ -5,7 +5,7 @@
  * runtime for any model recorded on a knowledge base row.
  */
 
-export const EMBEDDING_DIMENSIONS = 1536
+export const EMBEDDING_DIMENSIONS = 1536 as const
 
 export const DEFAULT_EMBEDDING_MODEL = 'text-embedding-3-small'