feat: add tenant bound restriction for IM dashboard and management pages

1. extract isTenantBound utility from user store logic
2. add disabled state to tenant select components across all IM pages
3. update policy tenant options logic to hide global option for bound tenants
4. add backend scope validation for IM admin operations

web/src/views/imOrg/model.ts

@@ -2,7 +2,7 @@ import { computed, ref } from 'vue';
 import { cloneDeep } from 'lodash-es';
 import { FormSchema } from '@/components/Form';
 import { useDictStore } from '@/store/modules/dict';
-import { loadImTenantOptions } from '@/views/imTenantOptions';
+import { isTenantBound, loadImTenantOptions } from '@/views/imTenantOptions';
 
 const dict = useDictStore();
 
@@ -77,6 +77,7 @@ export const departmentSchemas = ref<FormSchema[]>([
     componentProps: {
       clearable: false,
       options: computed(() => tenantOptions.value),
+      disabled: isTenantBound(),
       placeholder: '请选择商户',
     },
   },