test(web): feature Gherkin jetable pour valider le pipeline preprocessor

Étape 2 de l'expérimentation — un seul scénario minimal (remplir
email/password sur l'écran de connexion) pour vérifier que
addCucumberPreprocessorPlugin@22.2.0 + l'esbuild plugin fonctionnent
de bout en bout, pas juste au chargement. Steps volontairement
autonomes dans login-smoke.steps.ts (pas de fichier partagé) — tout
ce fichier est prévu pour être supprimé une fois validé.

cypress.config.ts : specPattern couvre maintenant *.cy.ts ET *.feature
en parallèle (le reste de la suite reste en .cy.ts classique pour
l'instant).

Testé en local jusqu'au mur GPU/Electron habituel de cet
environnement (chargement de la config + bundling esbuild passent,
pas d'ERR_REQUIRE_ESM) — la vraie exécution du scénario reste à
vérifier via la CI.

apps/web/cypress.config.ts

@@ -1,9 +1,18 @@
+import { addCucumberPreprocessorPlugin } from "@badeball/cypress-cucumber-preprocessor";
+import { createEsbuildPlugin } from "@badeball/cypress-cucumber-preprocessor/esbuild";
+import createBundler from "@bahmutov/cypress-esbuild-preprocessor";
 import { defineConfig } from "cypress";
 
 export default defineConfig({
   e2e: {
     baseUrl: "http://localhost:5173",
-    setupNodeEvents(on) {
+    // Experimental — testing whether real Gherkin .feature files work with
+    // this preprocessor version (see experiment/cucumber-cypress). Only one
+    // throwaway feature exists right now (login.feature); the rest of the
+    // suite is still plain .cy.ts, matched by the default `**/*.cy.ts`
+    // pattern alongside `**/*.feature`.
+    specPattern: ["cypress/e2e/**/*.cy.ts", "cypress/e2e/**/*.feature"],
+    async setupNodeEvents(on, config) {
       // Disable GPU for headless/sandboxed environments (e.g. CI containers)
       // where no GPU device is available.
       on("before:browser:launch", (browser, launchOptions) => {
@@ -12,6 +21,16 @@ export default defineConfig({
         }
         return launchOptions;
       });
+
+      await addCucumberPreprocessorPlugin(on, config);
+      on(
+        "file:preprocessor",
+        createBundler({
+          plugins: [createEsbuildPlugin(config)],
+        }),
+      );
+
+      return config;
     },
   },
 });

apps/web/cypress/e2e/login-smoke.feature

@@ -0,0 +1,12 @@
+Feature: Login screen (throwaway smoke test)
+  Just checking that Gherkin + Cypress actually work end to end with the
+  currently installed preprocessor version — not meant to stay in the
+  suite long-term.
+
+  Scenario: A visitor can type their credentials into the login screen
+    Given I am not signed in
+    When I visit "/login"
+    And I fill in the "email" field with "alice@example.com"
+    And I fill in the "password" field with "correct-horse-battery-staple"
+    Then the "email" field should have the value "alice@example.com"
+    And the "password" field should have the value "correct-horse-battery-staple"

apps/web/cypress/e2e/login-smoke.steps.ts

@@ -0,0 +1,21 @@
+import { Given, Then, When } from "@badeball/cypress-cucumber-preprocessor";
+
+// Throwaway smoke test — see login-smoke.feature. Steps are deliberately
+// minimal/self-contained here rather than shared, since this whole file is
+// meant to be deleted once it's proven the preprocessor works.
+
+Given("I am not signed in", () => {
+  cy.intercept("GET", "**/auth/me", { statusCode: 401 });
+});
+
+When("I visit {string}", (path: string) => {
+  cy.visit(path);
+});
+
+When("I fill in the {string} field with {string}", (fieldId: string, value: string) => {
+  cy.get(`#${fieldId}`).type(value);
+});
+
+Then("the {string} field should have the value {string}", (fieldId: string, value: string) => {
+  cy.get(`#${fieldId}`).should("have.value", value);
+});