refactor: remove username from User model, login by email only

tests/unit/app/users/user-pages.test.ts

@@ -51,7 +51,6 @@ describe("user pages localization", () => {
         {
           id: "user-1",
           name: "Ada Lovelace",
-          username: "ada",
           email: "ada@example.test",
           role: "ADMIN",
           isActive: true,
@@ -59,7 +58,6 @@ describe("user pages localization", () => {
         {
           id: "user-2",
           name: "Grace Hopper",
-          username: "grace",
           email: "grace@example.test",
           role: "STAFF",
           isActive: false,
@@ -78,7 +76,6 @@ describe("user pages localization", () => {
 
     // Table headers from dictionary
     expect(html).toContain("Nombre")
-    expect(html).toContain("Usuario")
     expect(html).toContain("Correo electrónico")
     expect(html).toContain("Rol")
     expect(html).toContain("Estado")
@@ -94,10 +91,8 @@ describe("user pages localization", () => {
 
     // User data is never translated
     expect(html).toContain("Ada Lovelace")
-    expect(html).toContain("ada")
     expect(html).toContain("ada@example.test")
     expect(html).toContain("Grace Hopper")
-    expect(html).toContain("grace")
     expect(html).toContain("grace@example.test")
 
     // Canonical role values must NOT appear as display text
@@ -133,7 +128,6 @@ describe("user pages localization", () => {
         {
           id: "user-1",
           name: "Ada Lovelace",
-          username: "ada",
           email: "ada@example.test",
           role: "MANAGER",
           isActive: true,
@@ -150,7 +144,6 @@ describe("user pages localization", () => {
     expect(html).toContain("Users")
     expect(html).toContain("Add User")
     expect(html).toContain("Name")
-    expect(html).toContain("Username")
     expect(html).toContain("Email")
     expect(html).toContain("Role")
     expect(html).toContain("Status")
@@ -172,7 +165,6 @@ describe("user pages localization", () => {
         {
           id: "user-1",
           name: "Test User",
-          username: "testuser",
           email: "test@example.test",
           role: "UNKNOWN_ROLE",
           isActive: true,