feat(clients): selective bulk attach + new bulk detach

Inbounds page:
- AttachClientsModal now shows a per-client selection table (email,
  comment, enabled tag) with search and a live "selected of total"
  counter; all clients are pre-selected so the old "attach all"
  workflow stays a single OK click.
- New DetachClientsModal on the inbound row menu lets you pick which
  clients to remove from that inbound (records are kept so they can be
  re-attached later; for full removal use Delete).

Clients page:
- New "Attach (N)" bulk-action button + BulkAttachInboundsModal that
  attaches selected clients to one or more multi-user inbounds.
- New "Detach (N)" bulk-action button + BulkDetachInboundsModal that
  removes selected clients from chosen inbounds; (email, inbound) pairs
  where the client isn't attached are silently skipped.

Backend adds POST /panel/api/clients/bulkDetach, wrapping the existing
Detach service for each email and reporting per-email
detached/skipped/errors. ClientRecord rows are kept on detach to match
the single-client endpoint; bulkDel remains the path for full removal.

frontend/src/pages/clients/ClientsPage.tsx

@@ -42,6 +42,7 @@ import {
   TagsOutlined,
   TeamOutlined,
   UsergroupAddOutlined,
+  UsergroupDeleteOutlined,
 } from '@ant-design/icons';
 
 import { useTheme } from '@/hooks/useTheme';
@@ -62,6 +63,8 @@ const ClientBulkAdjustModal = lazy(() => import('./ClientBulkAdjustModal'));
 const FilterDrawer = lazy(() => import('./FilterDrawer'));
 const SubLinksModal = lazy(() => import('./SubLinksModal'));
 const BulkAssignGroupModal = lazy(() => import('./BulkAssignGroupModal'));
+const BulkAttachInboundsModal = lazy(() => import('./BulkAttachInboundsModal'));
+const BulkDetachInboundsModal = lazy(() => import('./BulkDetachInboundsModal'));
 import { emptyFilters, activeFilterCount } from './filters';
 import type { ClientFilters } from './filters';
 import './ClientsPage.css';
@@ -149,7 +152,7 @@ export default function ClientsPage() {
     setQuery,
     inbounds, onlines, loading, fetched, subSettings,
     ipLimitEnable, tgBotEnable, expireDiff, trafficDiff, pageSize,
-    create, update, remove, bulkDelete, bulkAdjust, bulkAssignGroup, attach, detach,
+    create, update, remove, bulkDelete, bulkAdjust, bulkAssignGroup, attach, bulkAttach, detach, bulkDetach,
     resetTraffic, resetAllTraffics, delDepleted, setEnable,
     applyTrafficEvent, applyClientStatsEvent,
     hydrate,
@@ -173,6 +176,8 @@ export default function ClientsPage() {
   const [bulkAdjustOpen, setBulkAdjustOpen] = useState(false);
   const [subLinksOpen, setSubLinksOpen] = useState(false);
   const [bulkGroupOpen, setBulkGroupOpen] = useState(false);
+  const [bulkAttachOpen, setBulkAttachOpen] = useState(false);
+  const [bulkDetachOpen, setBulkDetachOpen] = useState(false);
   const [selectedRowKeys, setSelectedRowKeys] = useState<string[]>([]);
 
   const initial = readFilterState();
@@ -789,6 +794,12 @@ export default function ClientsPage() {
                               <Button icon={<TagsOutlined />} onClick={() => setBulkGroupOpen(true)}>
                                 {t('pages.clients.assignGroupSelected', { count: selectedRowKeys.length })}
                               </Button>
+                              <Button icon={<UsergroupAddOutlined />} onClick={() => setBulkAttachOpen(true)}>
+                                {t('pages.clients.attachSelected', { count: selectedRowKeys.length })}
+                              </Button>
+                              <Button danger icon={<UsergroupDeleteOutlined />} onClick={() => setBulkDetachOpen(true)}>
+                                {t('pages.clients.detachSelected', { count: selectedRowKeys.length })}
+                              </Button>
                               <Button icon={<LinkOutlined />} onClick={() => setSubLinksOpen(true)}>
                                 {t('pages.clients.subLinksSelected', { count: selectedRowKeys.length })}
                               </Button>
@@ -1157,6 +1168,38 @@ export default function ClientsPage() {
             }}
           />
         </LazyMount>
+        <LazyMount when={bulkAttachOpen}>
+          <BulkAttachInboundsModal
+            open={bulkAttachOpen}
+            count={selectedRowKeys.length}
+            inbounds={inbounds}
+            onOpenChange={setBulkAttachOpen}
+            onSubmit={async (inboundIds) => {
+              const msg = await bulkAttach([...selectedRowKeys], inboundIds);
+              if (msg?.success) {
+                setSelectedRowKeys([]);
+                return msg.obj ?? { attached: [], skipped: [], errors: [] };
+              }
+              return null;
+            }}
+          />
+        </LazyMount>
+        <LazyMount when={bulkDetachOpen}>
+          <BulkDetachInboundsModal
+            open={bulkDetachOpen}
+            count={selectedRowKeys.length}
+            inbounds={inbounds}
+            onOpenChange={setBulkDetachOpen}
+            onSubmit={async (inboundIds) => {
+              const msg = await bulkDetach([...selectedRowKeys], inboundIds);
+              if (msg?.success) {
+                setSelectedRowKeys([]);
+                return msg.obj ?? { detached: [], skipped: [], errors: [] };
+              }
+              return null;
+            }}
+          />
+        </LazyMount>
         <LazyMount when={filterDrawerOpen}>
           <FilterDrawer
             open={filterDrawerOpen}