fix: use get_module_dbname for discount db in init_free_customers

wwwroot/api/init_free_customers.dspy

@@ -5,6 +5,7 @@ if not userorgid:
     return {'widgettype': 'Error', 'options': {'title': 'Error', 'message': '请先登录', 'timeout': 3}}
 
 count = 0
+disc_dbname = get_module_dbname('discount')
 async with DBPools().sqlorContext('sage') as sor:
     # Get all users (filtered by org if not owner)
     if userorgid == '0':
@@ -17,7 +18,7 @@ async with DBPools().sqlorContext('sage') as sor:
     if not users:
         return {'widgettype': 'Message', 'options': {'title': '提示', 'message': '该机构下无用户', 'type': 'warning', 'timeout': 3}}
 
-    async with DBPools().sqlorContext('discount') as disc_sor:
+    async with DBPools().sqlorContext(disc_dbname) as disc_sor:
         for u in users:
             existing = await disc_sor.sqlExe(
                 'SELECT id FROM discount_customer_bind WHERE customerid = ${cid}$',