fix(files): make targetFolder optional in move file contract

Author: waleedlatif1

apps/sim/lib/api/contracts/tools/file.ts

@@ -37,7 +37,7 @@ export const fileManageMoveBodySchema = z.object({
   operation: z.literal('move'),
   workspaceId: z.string().min(1).optional(),
   fileId: z.string().min(1, 'fileId is required for move operation'),
-  targetFolder: z.string(), // empty string = workspace root, "reports" or "reports/Q1" for nested
+  targetFolder: z.string().optional().default(''), // empty string = workspace root, "reports" or "reports/Q1" for nested
 })
 
 export type FileManageMoveBody = z.input<typeof fileManageMoveBodySchema>