refactor: Remove unused exports

Remove setPrimaryAccountSchema from email-account.validators.js and
requireOwnerOrAdmin from roleMiddleware.js — both have zero imports.

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

src/validators/email-account.validators.js

@@ -21,7 +21,3 @@ export const updateEmailAccountSchema = z.object({
   isActive: z.boolean().optional(),
 });
 
-// Set primary account schema
-export const setPrimaryAccountSchema = z.object({
-  accountId: z.string().uuid('Neplatný formát account ID'),
-});