chore: update Prisma and dependencies, add initial migration and tests

- Updated Prisma and @prisma/client to version 6.19.2 in package.json and yarn.lock.
- Added package extensions for @prisma/client in .yarnrc.yml.
- Updated backend README.md for clearer setup instructions.
- Created initial migration for Game, Platform, and related tables in Prisma.
- Added migration lock file for version control.
- Implemented tests for Game model using Vitest, including creation and unique slug constraint checks.

backend/tests/models/game.spec.ts

@@ -0,0 +1,92 @@
+import fs from 'fs';
+import os from 'os';
+import path from 'path';
+import { execSync } from 'child_process';
+import { describe, beforeAll, afterAll, it, expect } from 'vitest';
+// Import PrismaClient dynamically after running `prisma generate`
+// to allow the test setup to run `prisma generate`/`prisma migrate` first.
+
+// Nota: Estos tests siguen TDD. Al principio deben FALLAR hasta que se creen migraciones.
+
+describe('Prisma / Game model', () => {
+  const tmpDir = os.tmpdir();
+  const dbFile = path.join(
+    tmpDir,
+    `quasar-test-${Date.now()}-${Math.random().toString(36).slice(2)}.db`
+  );
+  const databaseUrl = `file:${dbFile}`;
+  let prisma: any;
+
+  beforeAll(async () => {
+    // Asegurarse de que la DB de prueba no exista antes de empezar
+    try {
+      fs.unlinkSync(dbFile);
+    } catch (e) {
+      /* ignore */
+    }
+
+    // Apuntar Prisma a la DB temporal
+    process.env.DATABASE_URL = databaseUrl;
+
+    // Ejecutar migraciones contra la DB de prueba
+    // Esto fallará si no hay migraciones: esperado en la fase TDD inicial
+    execSync('yarn prisma migrate deploy --schema=./prisma/schema.prisma', {
+      stdio: 'inherit',
+      cwd: path.resolve(__dirname, '..', '..'),
+    });
+
+    // Intentar requerir el cliente generado; si no existe, intentar generarlo (fallback)
+    let GeneratedPrismaClient;
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      GeneratedPrismaClient = require('@prisma/client').PrismaClient;
+    } catch (e) {
+      try {
+        execSync('yarn prisma generate --schema=./prisma/schema.prisma', {
+          stdio: 'inherit',
+          cwd: path.resolve(__dirname, '..', '..'),
+        });
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
+        GeneratedPrismaClient = require('@prisma/client').PrismaClient;
+      } catch (err) {
+        // Si generation falla (por ejemplo PnP), reintentar require para mostrar mejor error
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
+        GeneratedPrismaClient = require('@prisma/client').PrismaClient;
+      }
+    }
+    prisma = new GeneratedPrismaClient();
+    await prisma.$connect();
+  });
+
+  afterAll(async () => {
+    if (prisma) {
+      await prisma.$disconnect();
+    }
+    try {
+      fs.unlinkSync(dbFile);
+    } catch (e) {
+      /* ignore */
+    }
+  });
+
+  it('can create a Game and read title/slug', async () => {
+    const created = await prisma.game.create({ data: { title: 'Test Game', slug: 'test-game' } });
+    const found = await prisma.game.findUnique({ where: { id: created.id } });
+    expect(found).toBeTruthy();
+    expect(found?.title).toBe('Test Game');
+    expect(found?.slug).toBe('test-game');
+  });
+
+  it('enforces unique slug constraint', async () => {
+    const slug = `unique-${Date.now()}`;
+    await prisma.game.create({ data: { title: 'G1', slug } });
+
+    let threw = false;
+    try {
+      await prisma.game.create({ data: { title: 'G2', slug } });
+    } catch (err) {
+      threw = true;
+    }
+    expect(threw).toBe(true);
+  });
+});