chg: [internal] Switch admin setting name column to unique index

INSTALL/MYSQL.sql

@@ -11,7 +11,7 @@ CREATE TABLE IF NOT EXISTS `admin_settings` (
   `setting` varchar(255) COLLATE utf8_bin NOT NULL,
   `value` text COLLATE utf8_bin NOT NULL,
   PRIMARY KEY (`id`),
-  INDEX `setting` (`setting`)
+  UNIQUE INDEX `setting` (`setting`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
 CREATE TABLE IF NOT EXISTS `allowedlist` (

db_schema.json

@@ -7739,7 +7739,7 @@
     "indexes": {
         "admin_settings": {
             "id": true,
-            "setting": false
+            "setting": true
         },
         "allowedlist": {
             "id": true