fix(commerce-backend): agregar dummies de build para vars de Google OAuth

npm run build (medusa build) carga medusa-config.ts, que ahora exige
GOOGLE_CLIENT_ID/GOOGLE_CLIENT_SECRET/GOOGLE_CALLBACK_URL via required().
Sin valores dummy en el builder stage, el build fallaba con "Error in
loading config: La variable GOOGLE_CLIENT_ID es obligatoria" -- mismo
patron ya usado para JWT_SECRET/MEILISEARCH_API_KEY.

workloads/commerce-backend/Dockerfile

@@ -23,7 +23,10 @@ ENV CI=true \
     S3_BUCKET=ari-shopping \
     S3_ENDPOINT=http://127.0.0.1:9000 \
     MEILISEARCH_HOST=http://127.0.0.1:7700 \
-    MEILISEARCH_API_KEY=build-only-meili-key
+    MEILISEARCH_API_KEY=build-only-meili-key \
+    GOOGLE_CLIENT_ID=build-only-google-client-id \
+    GOOGLE_CLIENT_SECRET=build-only-google-client-secret \
+    GOOGLE_CALLBACK_URL=http://localhost:9000/auth/customer/google/callback
 
 COPY package.json package-lock.json .npmrc ./
 

workloads/commerce-backend/medusa-config.ts

@@ -157,6 +157,30 @@ module.exports = defineConfig({
         ],
       },
     },
+    {
+      resolve: "@medusajs/medusa/auth",
+      options: {
+        providers: [
+          // emailpass se declara explicito junto con google -- una vez
+          // que el modulo auth se customiza, la doc no deja claro si el
+          // provider default (emailpass) se sigue registrando solo.
+          {
+            resolve: "@medusajs/medusa/auth-emailpass",
+            id: "emailpass",
+            options: {},
+          },
+          {
+            resolve: "@medusajs/medusa/auth-google",
+            id: "google",
+            options: {
+              clientId: required("GOOGLE_CLIENT_ID"),
+              clientSecret: required("GOOGLE_CLIENT_SECRET"),
+              callbackUrl: required("GOOGLE_CALLBACK_URL"),
+            },
+          },
+        ],
+      },
+    },
   ],
 
   // ADR 0006 Etapa 2. Sin required(): a diferencia de S3/DB, Meilisearch