feat: implement multi-tenant member management and UI improvements

- Add multi-tenant support (isAddTenant, isRemoveTenant) to backend UpdateUser API.
- Update UserRepository to support searching in company_codes array.
- Implement table sorting and align search bar layout in adminfront.
- Add 'Assign Existing Member' and 'Exclude from Organization' features to TenantUsersPage.
- Auto-populate tenantSlug in UserCreatePage via query parameters.
- Add necessary localization keys for new UI elements.

Resolves #644, #639, #642, #641

adminfront/src/locales/en.toml

@@ -1176,14 +1176,49 @@ primary = "Representative Affiliated Tenant"
 title = "Affiliation & Organization Info"
 
 [ui.admin.users.list]
-add = "User Add"
+add = "Add User"
+add_to_tenant = "Add to Tenant"
 bulk_import = "Bulk Import"
-empty = "Empty"
-fetch_error = "Fetch Error"
-search_placeholder = "Search Placeholder"
-subtitle = "Subtitle"
+empty = "No users found."
+fetch_error = "Failed to fetch user list."
+search_label = "Search Users"
+search_placeholder = "Search by name or email..."
+subtitle = "View and manage system users."
 toggle_status = "{{name}} active status"
-title = "User Manage"
+title = "User Management"
+
+[msg.admin.users]
+add_tenant_confirm = "Are you sure you want to add '{{name}}' to '{{tenant}}' tenant?"
+add_tenant_error = "An error occurred while adding the tenant."
+add_tenant_success = "Successfully added to the tenant."
+export_error = "Failed to export users."
+status_error = "Failed to change user status."
+self_delete_blocked = "You cannot delete your own account."
+
+[ui.admin.tenants.members]
+add_existing = "Assign Existing Member"
+create_new = "Create New Member"
+remove = "Exclude from Organization"
+title = "Tenant Members ({{count}})"
+view_profile = "View Profile"
+
+[ui.admin.tenants.members.table]
+actions = "ACTIONS"
+email = "EMAIL"
+name = "NAME"
+role = "ROLE"
+status = "STATUS"
+
+[msg.admin.tenants.members]
+empty = "No members in this organization."
+remove_confirm = "Are you sure you want to exclude '{{name}}' from this organization?"
+remove_error = "An error occurred while excluding from organization."
+remove_success = "Successfully excluded from organization."
+
+[ui.admin.tenants.list]
+search_label = "Search Tenants"
+search_placeholder = "Search by name or slug..."
+title = "Tenant List"
 
 [ui.admin.users.list.breadcrumb]
 list = "List"