feat(backend): add standalone data plane

Replace the Supabase application data plane with the Node/PostgreSQL API, migrate mobile, admin, web, and MCP callers, add controlled cutover tooling, and define hardened Dokploy infrastructure.

apps/mobile/src/lib/accountOperationsApi.ts

@@ -0,0 +1,19 @@
+import { apiClient } from './apiClient';
+
+export interface AccountOperationResponse {
+    success: true;
+    message: string;
+}
+
+export interface SubscriptionSyncResponse {
+    success: true;
+    is_premium: boolean;
+}
+
+export const accountOperationsApi = {
+    deleteRelationship: () => apiClient.delete<AccountOperationResponse>('/v1/couple/data'),
+    resetProgress: () => apiClient.delete<AccountOperationResponse>('/v1/couple/progress'),
+    deleteAccount: () => apiClient.delete<AccountOperationResponse>('/v1/me'),
+    syncSubscription: () => apiClient.post<SubscriptionSyncResponse>('/v1/me/subscription/sync'),
+};
+