refactor(frontend): Remove '/api' prefix from all API calls to align with backend URL convention

- Updated all API endpoint strings in 'frontend/src' (via sed and manual fixes) to remove the '/api/' prefix.
- Manually fixed 'Timeline.tsx' absolute URLs to use the 'api' subdomain and correct path.
- Manually fixed 'useAuth.ts' logout fetch URLs.
- Updated 'HelpApiDocs.tsx' sandbox URL.
- This change, combined with the backend URL update, fully transitions the application to use subdomain-based routing (e.g., 'http://api.lvh.me:8000/resource/') instead of path-prefix routing (e.g., 'http://api.lvh.me:8000/api/resource/').

frontend/src/pages/EmailTemplates.tsx

@@ -62,7 +62,7 @@ const EmailTemplates: React.FC = () => {
   const { data: templates = [], isLoading, error } = useQuery<EmailTemplate[]>({
     queryKey: ['email-templates'],
     queryFn: async () => {
-      const { data } = await api.get('/api/email-templates/');
+      const { data } = await api.get('/email-templates/');
       return data.map((t: any) => ({
         id: String(t.id),
         name: t.name,
@@ -85,7 +85,7 @@ const EmailTemplates: React.FC = () => {
   // Delete template mutation
   const deleteMutation = useMutation({
     mutationFn: async (templateId: string) => {
-      await api.delete(`/api/email-templates/${templateId}/`);
+      await api.delete(`/email-templates/${templateId}/`);
     },
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['email-templates'] });
@@ -97,7 +97,7 @@ const EmailTemplates: React.FC = () => {
   // Duplicate template mutation
   const duplicateMutation = useMutation({
     mutationFn: async (templateId: string) => {
-      const { data } = await api.post(`/api/email-templates/${templateId}/duplicate/`);
+      const { data } = await api.post(`/email-templates/${templateId}/duplicate/`);
       return data;
     },
     onSuccess: () => {