refactor: remove security-related hooks and pages

- Deleted `useSecurity.ts` hook which managed authentication users, providers, and policies.
- Removed `Policies.tsx`, `Providers.tsx`, and `Users.tsx` pages that utilized the above hook.
- Cleaned up the `index.tsx` file in the Security section to remove references to the deleted pages.
- Updated mock data by removing unused properties related to forward authentication.

frontend/src/App.tsx

@@ -13,7 +13,6 @@ const ProxyHosts = lazy(() => import('./pages/ProxyHosts'))
 const RemoteServers = lazy(() => import('./pages/RemoteServers'))
 const ImportCaddy = lazy(() => import('./pages/ImportCaddy'))
 const Certificates = lazy(() => import('./pages/Certificates'))
-const Security = lazy(() => import('./pages/Security'))
 const SystemSettings = lazy(() => import('./pages/SystemSettings'))
 const Account = lazy(() => import('./pages/Account'))
 const Settings = lazy(() => import('./pages/Settings'))
@@ -51,7 +50,6 @@ export default function App() {
               <Route path="uptime" element={<Uptime />} />
               <Route path="notifications" element={<Notifications />} />
               <Route path="import" element={<ImportCaddy />} />
-              <Route path="security" element={<Security />} />
 
               {/* Settings Routes */}
               <Route path="settings" element={<Settings />}>