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/components/EmailTemplateSelector.tsx

@@ -32,7 +32,7 @@ const EmailTemplateSelector: React.FC<EmailTemplateSelectorProps> = ({
     queryFn: async () => {
       const params = new URLSearchParams();
       if (category) params.append('category', category);
-      const { data } = await api.get(`/api/email-templates/?${params.toString()}`);
+      const { data } = await api.get(`/email-templates/?${params.toString()}`);
       return data.map((t: any) => ({
         id: String(t.id),
         name: t.name,