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/api/test/couples.repository.integration.test.ts

@@ -0,0 +1,64 @@
+import { randomUUID } from 'node:crypto';
+import { readFile } from 'node:fs/promises';
+import { Pool } from 'pg';
+import { afterAll, beforeAll, describe, expect, it } from 'vitest';
+import { PostgresCoupleRepository } from '../src/domains/couples/repository.js';
+
+const databaseUrl = process.env.DATABASE_URL;
+const localDatabase = databaseUrl ? ['127.0.0.1', 'localhost', '::1'].includes(new URL(databaseUrl).hostname) : false;
+if (databaseUrl && !localDatabase) {
+  throw new Error('Couples integration tests only permit a localhost DATABASE_URL');
+}
+
+describe.skipIf(!databaseUrl || !localDatabase)('PostgresCoupleRepository', () => {
+  const adminPool = new Pool({ connectionString: databaseUrl });
+  const schema = `couples_test_${randomUUID().replaceAll('-', '')}`;
+  let pool: Pool;
+  let repository: PostgresCoupleRepository;
+  const alice = '11111111-1111-4111-8111-111111111111';
+  const bob = '22222222-2222-4222-8222-222222222222';
+  const charlie = '33333333-3333-4333-8333-333333333333';
+
+  beforeAll(async () => {
+    await adminPool.query(`CREATE SCHEMA "${schema}"`);
+    const isolatedUrl = new URL(databaseUrl!);
+    isolatedUrl.searchParams.set('options', `-c search_path=${schema}`);
+    pool = new Pool({ connectionString: isolatedUrl.toString() });
+    repository = new PostgresCoupleRepository(isolatedUrl.toString());
+
+    for (const migrationName of ['0000_identity_and_feature_interests.sql', '0001_couples.sql']) {
+      const migration = await readFile(new URL(`../drizzle/${migrationName}`, import.meta.url), 'utf8');
+      for (const statement of migration.split('--> statement-breakpoint')) {
+        if (statement.trim()) await pool.query(statement);
+      }
+    }
+    await pool.query(
+      `insert into profiles (id, name) values ($1, 'Alice'), ($2, 'Bob'), ($3, 'Charlie')`,
+      [alice, bob, charlie],
+    );
+  });
+
+  afterAll(async () => {
+    await repository.close();
+    await pool.end();
+    await adminPool.query(`DROP SCHEMA "${schema}" CASCADE`);
+    await adminPool.end();
+  });
+
+  it('creates, joins, reads the partner, enforces capacity, and cancels both members atomically', async () => {
+    const coupleId = 'aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa';
+    await repository.create(alice, coupleId, 'ABCD2345');
+    await repository.join(bob, 'ABCD2345');
+
+    await expect(repository.getState(alice)).resolves.toMatchObject({
+      couple: { id: coupleId, invite_code: 'ABCD2345' },
+      partner: { id: bob, name: 'Bob', couple_id: coupleId },
+    });
+    await expect(repository.join(charlie, 'ABCD2345')).rejects.toMatchObject({ code: 'couple_full' });
+
+    await repository.cancel(alice);
+    await expect(repository.getState(alice)).resolves.toEqual({ couple: null, partner: null });
+    await expect(repository.getState(bob)).resolves.toEqual({ couple: null, partner: null });
+    expect((await pool.query('select count(*)::int as count from couples')).rows[0].count).toBe(0);
+  });
+});