fix: 移除所有弹框遮罩层点击关闭 — 防止输入时误触关闭

涉及文件 (12处):
- InstancePage.tsx: 添加数据源弹框
- UsersPage.tsx: 新建/编辑/重置密码/详情弹框 (4处)
- RolesPage.tsx: 克隆角色弹框
- InstanceGroupPage.tsx: 新建/编辑/关联实例/关联用户弹框 (4处)
- SlowQueryPage.tsx: 查询对比弹框
- RedisDetailPage.tsx: 键详情/新增键弹框 (2处)

改动: 遮罩层div移除onClick，只能通过X按钮或取消按钮关闭

frontend/src/pages/UsersPage.tsx

@@ -590,7 +590,7 @@ function CreateUserModal({ onClose, onCreated, setToast }: { onClose: () => void
   };
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50" onClick={onClose}>
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
       <div className="w-full max-w-md bg-[var(--dg-bg-secondary)] border border-[var(--dg-border)] rounded-xl p-6 shadow-xl" onClick={e => e.stopPropagation()}>
         <div className="flex items-center justify-between mb-5">
           <h2 className="text-lg font-semibold">新建用户</h2>
@@ -677,7 +677,7 @@ function EditUserModal({ user, onClose, onUpdated, setToast }: { user: UserItem;
   };
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50" onClick={onClose}>
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
       <div className="w-full max-w-md bg-[var(--dg-bg-secondary)] border border-[var(--dg-border)] rounded-xl p-6 shadow-xl" onClick={e => e.stopPropagation()}>
         <div className="flex items-center justify-between mb-5">
           <h2 className="text-lg font-semibold">编辑用户</h2>
@@ -758,7 +758,7 @@ function ResetPasswordModal({ user, onClose, setToast }: { user: UserItem; onClo
   };
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50" onClick={onClose}>
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
       <div className="w-full max-w-sm bg-[var(--dg-bg-secondary)] border border-[var(--dg-border)] rounded-xl p-6 shadow-xl" onClick={e => e.stopPropagation()}>
         <div className="flex items-center justify-between mb-5">
           <h2 className="text-lg font-semibold flex items-center gap-2"><KeyRound className="w-5 h-5 text-yellow-400" /> 重置密码</h2>
@@ -795,7 +795,7 @@ function UserDetailModal({ user, onClose }: { user: UserItem; onClose: () => voi
   const activities = useMemo(() => generateMockActivities(user.id), [user.id]);
 
   return (
-    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50" onClick={onClose}>
+    <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/50">
       <div className="w-full max-w-lg bg-[var(--dg-bg-secondary)] border border-[var(--dg-border)] rounded-xl p-6 shadow-xl max-h-[80vh] overflow-y-auto" onClick={e => e.stopPropagation()}>
         <div className="flex items-center justify-between mb-5">
           <h2 className="text-lg font-semibold">用户详情</h2>