Fix TypeScript build errors

- HelpPage: remove unused navigate import
- AdminClientsPage: align state type with API response (hasCustomTemplate vs hasCustom)

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

frontend/src/pages/HelpPage.tsx

@@ -1,5 +1,4 @@
 import { useState } from 'react'
-import { useNavigate } from 'react-router-dom'
 import { useAuthStore } from '../stores/useAuthStore'
 
 // ── Section types ──────────────────────────────────────────────────────────────
@@ -365,7 +364,6 @@ const SECTIONS: Section[] = [
 // ── Page ───────────────────────────────────────────────────────────────────────
 
 export default function HelpPage() {
-  const navigate = useNavigate()
   const user = useAuthStore(s => s.user)
   const isAdmin = user?.role === 'admin'
   const [activeId, setActiveId] = useState('overview')

frontend/src/pages/admin/AdminClientsPage.tsx

@@ -182,7 +182,7 @@ export default function AdminClientsPage() {
 // ── Export template per-client ─────────────────────────────────────────────────
 
 function ClientExportTemplate({ clientId }: { clientId: string }) {
-  const [data, setData] = useState<{ template: ExportTemplateColumn[]; hasCustom: boolean; fields: string[] } | null>(null)
+  const [data, setData] = useState<{ template: ExportTemplateColumn[]; hasCustomTemplate: boolean; fields: string[] } | null>(null)
 
   useEffect(() => {
     getClientExportTemplate(clientId).then(setData).catch(() => {})
@@ -198,8 +198,8 @@ function ClientExportTemplate({ clientId }: { clientId: string }) {
         Export CSV template
       </div>
       <ExportTemplateEditor
-        template={data.hasCustom ? data.template : null}
-        hasCustom={data.hasCustom}
+        template={data.hasCustomTemplate ? data.template : null}
+        hasCustom={data.hasCustomTemplate}
         internalFields={data.fields}
         onDetect={file => detectClientExportTemplate(clientId, file)}
         onSave={async tpl => { await saveClientExportTemplate(clientId, tpl); await reload() }}