Tests: couverture Cypress pour les préférences utilisateur (step 4/4)

- user-preferences.cy.ts: défaut SYSTEM, thème sauvegardé restitué et
  appliqué au document, autosave sans bouton "Enregistrer"
- sidebar.cy.ts: 4 pages de paramètres (libellé "Préférences
  alimentaires" renommé + nouvelle entrée "Préférences utilisateur")
- auth.cy.ts/onboarding.cy.ts: corrige un intercept **/planning/current
  périmé (route supprimée dans la PR précédente) — masqué jusqu'ici car
  aucune assertion n'en dépendait directement, mais provoquait un appel
  réseau non mocké

apps/web/cypress/e2e/auth.cy.ts

@@ -76,7 +76,7 @@ describe("Signup", () => {
 describe("Login", () => {
   it("logs in and lands on the home page", () => {
     cy.intercept("GET", "**/auth/me", { statusCode: 401 });
-    cy.intercept("GET", "**/planning/current", { statusCode: 200, body: null });
+    cy.intercept("GET", /\/planning\?/, { statusCode: 200, body: null });
     cy.intercept("POST", "**/auth/login", {
       statusCode: 200,
       body: {
@@ -130,7 +130,7 @@ describe("Already authenticated", () => {
         dietId: null,
       },
     });
-    cy.intercept("GET", "**/planning/current", { statusCode: 200, body: null });
+    cy.intercept("GET", /\/planning\?/, { statusCode: 200, body: null });
 
     cy.visit("/login");
     cy.url().should("not.include", "/login");
@@ -150,7 +150,7 @@ describe("Already authenticated", () => {
         dietId: null,
       },
     });
-    cy.intercept("GET", "**/planning/current", { statusCode: 200, body: null });
+    cy.intercept("GET", /\/planning\?/, { statusCode: 200, body: null });
     cy.intercept("POST", "**/auth/logout", { statusCode: 204 }).as("logout");
 
     cy.visit("/");

apps/web/cypress/e2e/onboarding.cy.ts

@@ -16,7 +16,7 @@ const signupResponse = {
 function signupAndReachOnboarding() {
   cy.intercept("GET", "**/auth/me", { statusCode: 401 });
   cy.intercept("POST", "**/auth/signup", { statusCode: 201, body: signupResponse }).as("signup");
-  cy.intercept("GET", "**/planning/current", { statusCode: 200, body: null });
+  cy.intercept("GET", /\/planning\?/, { statusCode: 200, body: null });
 
   cy.visit("/signup");
   cy.get("#firstName").type("Alice");

apps/web/cypress/e2e/sidebar.cy.ts

@@ -13,7 +13,9 @@ const authenticatedProfile = {
 describe("Sidebar — settings menu and account menu", () => {
   beforeEach(() => {
     cy.intercept("GET", "**/auth/me", { statusCode: 200, body: authenticatedProfile });
-    cy.intercept("GET", "**/planning/current", { statusCode: 200, body: null });
+    // Not "**/planning*" — that glob also matches the Vite dev request for
+    // planning-page.scss (see planning-page.cy.ts for the same gotcha).
+    cy.intercept("GET", /\/planning\?/, { statusCode: 200, body: null });
   });
 
   it("no longer lists Foyer in the main nav", () => {
@@ -21,15 +23,24 @@ describe("Sidebar — settings menu and account menu", () => {
     cy.get(".app-sidebar__nav a").should("not.contain", "Foyer");
   });
 
-  it("reveals the three settings pages behind the Paramètres toggle", () => {
+  it("reveals the four settings pages behind the Paramètres toggle", () => {
     cy.visit("/");
 
     cy.contains("a", "Compte").should("not.exist");
     cy.contains("button", "Paramètres").click();
 
     cy.contains("a", "Compte").should("have.attr", "href", "/parametres/compte");
-    cy.contains("a", "Préférences").should("have.attr", "href", "/parametres/preferences");
+    cy.contains("a", "Préférences alimentaires").should(
+      "have.attr",
+      "href",
+      "/parametres/preferences",
+    );
     cy.contains("a", "Foyer").should("have.attr", "href", "/parametres/foyer");
+    cy.contains("a", "Préférences utilisateur").should(
+      "have.attr",
+      "href",
+      "/parametres/preferences-utilisateur",
+    );
   });
 
   it("opens the account menu from the greeting and links to Mon compte", () => {

apps/web/cypress/e2e/user-preferences.cy.ts

@@ -0,0 +1,54 @@
+// Mocks the API via cy.intercept — see auth.cy.ts for the rationale.
+
+const authenticatedProfile = {
+  id: 1,
+  firstName: "Alice",
+  lastName: "Martin",
+  email: "alice@example.com",
+  tokenVersion: 0,
+  houseId: null,
+  dietId: null,
+};
+
+describe("User preferences (/parametres/preferences-utilisateur)", () => {
+  beforeEach(() => {
+    cy.intercept("GET", "**/auth/me", { statusCode: 200, body: authenticatedProfile });
+  });
+
+  it("shows SYSTEM selected by default", () => {
+    cy.intercept("GET", "**/preferences", { statusCode: 200, body: { theme: "SYSTEM" } });
+
+    cy.visit("/parametres/preferences-utilisateur");
+
+    cy.contains("label", "Système").find("input[type=radio]").should("be.checked");
+    cy.contains("label", "Clair").find("input[type=radio]").should("not.be.checked");
+    cy.contains("label", "Sombre").find("input[type=radio]").should("not.be.checked");
+    // SYSTEM never sets an override — the OS/browser preference decides.
+    cy.get("html").should("not.have.attr", "data-theme");
+  });
+
+  it("shows the previously saved theme selected, and applies it to the document", () => {
+    cy.intercept("GET", "**/preferences", { statusCode: 200, body: { theme: "DARK" } });
+
+    cy.visit("/parametres/preferences-utilisateur");
+
+    cy.contains("label", "Sombre").find("input[type=radio]").should("be.checked");
+    cy.get("html").should("have.attr", "data-theme", "dark");
+  });
+
+  it("switching theme autosaves and applies immediately, no explicit save button", () => {
+    cy.intercept("GET", "**/preferences", { statusCode: 200, body: { theme: "SYSTEM" } });
+    cy.intercept("PATCH", "**/preferences", { statusCode: 200, body: { theme: "LIGHT" } }).as(
+      "updatePreferences",
+    );
+
+    cy.visit("/parametres/preferences-utilisateur");
+    cy.contains("button", "Enregistrer").should("not.exist");
+
+    cy.contains("label", "Clair").click();
+
+    cy.wait("@updatePreferences").its("request.body").should("deep.equal", { theme: "LIGHT" });
+    cy.contains("Enregistré ✓").should("be.visible");
+    cy.get("html").should("have.attr", "data-theme", "light");
+  });
+});