feat(deploy): add adult verification directory creation and permissions setup

- Enhanced deploy-backend.sh and update-backend.sh to create the adult verification directory under /opt/yourpart-data.
- Updated permissions for the new directory to ensure proper access control.
- Refactored file path handling in AdminService and SettingsService to utilize the new directory structure for adult verification files.

backend/utils/storagePaths.js

@@ -0,0 +1,26 @@
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+
+function getBackendRoot() {
+    return path.join(__dirname, '..');
+}
+
+export function getAdultVerificationBaseDir() {
+    if (process.env.ADULT_VERIFICATION_DIR && process.env.ADULT_VERIFICATION_DIR.trim()) {
+        return process.env.ADULT_VERIFICATION_DIR.trim();
+    }
+    if (process.env.YOURPART_PERSISTENT_DATA_DIR && process.env.YOURPART_PERSISTENT_DATA_DIR.trim()) {
+        return path.join(process.env.YOURPART_PERSISTENT_DATA_DIR.trim(), 'adult-verification');
+    }
+    if (process.env.STAGE === 'production' || process.env.NODE_ENV === 'production') {
+        return '/opt/yourpart-data/adult-verification';
+    }
+    return path.join(getBackendRoot(), 'images', 'adult-verification');
+}
+
+export function getLegacyAdultVerificationBaseDir() {
+    return path.join(getBackendRoot(), 'images', 'adult-verification');
+}