feat(web-admin): show copyable invite link after sending invite

After a platform admin sends an invite, the generated invite URL is
displayed inline with a one-click copy button so it can be shared via
any channel (email, WeChat, etc.). Link auto-dismisses when the invite
form is reopened.

Also adds i18n keys for invite link UI in en/zh.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

it0-web-admin/src/app/(admin)/tenants/[id]/page.tsx

@@ -225,6 +225,8 @@ export default function TenantDetailPage() {
   const [showInviteForm, setShowInviteForm] = useState(false);
   const [inviteEmail, setInviteEmail] = useState('');
   const [inviteRole, setInviteRole] = useState('viewer');
+  const [inviteLink, setInviteLink] = useState<string | null>(null);
+  const [linkCopied, setLinkCopied] = useState(false);
   const [form, setForm] = useState<TenantFormData>({
     name: '',
     plan: 'free',
@@ -297,12 +299,15 @@ export default function TenantDetailPage() {
 
   const sendInviteMutation = useMutation({
     mutationFn: (body: { email: string; role: string }) =>
-      apiClient(`/api/v1/admin/tenants/${id}/invites`, { method: 'POST', body }),
-    onSuccess: () => {
+      apiClient<{ token: string }>(`/api/v1/admin/tenants/${id}/invites`, { method: 'POST', body }),
+    onSuccess: (data) => {
       queryClient.invalidateQueries({ queryKey: queryKeys.tenants.invites(id) });
       setShowInviteForm(false);
       setInviteEmail('');
       setInviteRole('viewer');
+      const baseUrl = typeof window !== 'undefined' ? window.location.origin : '';
+      setInviteLink(`${baseUrl}/invite/${data.token}`);
+      setLinkCopied(false);
     },
   });
 
@@ -686,13 +691,39 @@ export default function TenantDetailPage() {
             <div className="flex items-center justify-between mb-4">
               <h2 className="text-lg font-semibold">{t('detail.invitations')}</h2>
               <button
-                onClick={() => setShowInviteForm(!showInviteForm)}
+                onClick={() => { setShowInviteForm(!showInviteForm); setInviteLink(null); }}
                 className="px-3 py-1 text-xs rounded-md bg-primary text-primary-foreground hover:opacity-90"
               >
                 {t('detail.inviteUser')}
               </button>
             </div>
 
+            {inviteLink && (
+              <div className="mb-4 p-4 border border-green-500/50 rounded-md bg-green-500/10 space-y-2">
+                <p className="text-sm font-medium text-green-700 dark:text-green-400">
+                  {t('detail.inviteLinkReady')}
+                </p>
+                <div className="flex gap-2 items-center">
+                  <input
+                    readOnly
+                    value={inviteLink}
+                    className="flex-1 px-2 py-1 text-xs font-mono bg-background border rounded-md"
+                  />
+                  <button
+                    onClick={() => {
+                      navigator.clipboard.writeText(inviteLink);
+                      setLinkCopied(true);
+                      setTimeout(() => setLinkCopied(false), 2000);
+                    }}
+                    className="px-3 py-1 text-xs rounded-md bg-primary text-primary-foreground hover:opacity-90 shrink-0"
+                  >
+                    {linkCopied ? t('detail.copied') : t('detail.copy')}
+                  </button>
+                </div>
+                <p className="text-xs text-muted-foreground">{t('detail.inviteLinkHint')}</p>
+              </div>
+            )}
+
             {showInviteForm && (
               <div className="mb-4 p-4 border rounded-md bg-muted/30 space-y-3">
                 <div>

it0-web-admin/src/i18n/locales/en/tenants.json

@@ -66,6 +66,10 @@
     "sendInvite": "Send Invite",
     "sending": "Sending...",
     "revoke": "Revoke",
+    "inviteLinkReady": "Invitation link generated — share it with the user:",
+    "copy": "Copy",
+    "copied": "Copied!",
+    "inviteLinkHint": "This link is valid for 7 days. The user can use it to create their account.",
     "suspendTenant": "Suspend Tenant",
     "activateTenant": "Activate Tenant",
     "viewAuditLog": "View Audit Log",

it0-web-admin/src/i18n/locales/zh/tenants.json

@@ -66,6 +66,10 @@
     "sendInvite": "发送邀请",
     "sending": "正在发送...",
     "revoke": "撤销",
+    "inviteLinkReady": "邀请链接已生成，将其发送给用户：",
+    "copy": "复制",
+    "copied": "已复制！",
+    "inviteLinkHint": "此链接有效期 7 天，用户通过该链接创建账号后即可登录。",
     "suspendTenant": "停用租户",
     "activateTenant": "激活租户",
     "viewAuditLog": "查看审计日志",