Add account settings page with passkey management

- /settings with profile, security, and account sections
- Profile: edit display name and bio
- Security: list passkeys with device labels, add/delete with
  last-passkey warning
- Account: email change with magic link verification, account
  deletion with username confirmation
- Settings link in nav for authenticated users
- E2E tests: auth guard, profile editing, passkey add/delete,
  last-passkey warning, account deletion, nav visibility
- i18n: full en + de translations for all settings UI

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/i18n/src/locales/de.ts

@@ -93,14 +93,6 @@ export default {
   journal: {
     title: "trails.cool",
     subtitle: "Dein Outdoor-Aktivitäten-Tagebuch",
-    nav: {
-      routes: "Routen",
-      activities: "Aktivitäten",
-      login: "Anmelden",
-      register: "Registrieren",
-      profile: "Profil",
-      logout: "Abmelden",
-    },
     welcome: "Willkommen,",
     addPasskeyPrompt: "Füge einen Passkey hinzu, um dich schneller auf diesem Gerät anzumelden.",
     addPasskey: "Passkey hinzufügen",
@@ -130,6 +122,50 @@ export default {
       linkToRoute: "Mit Route verknüpfen",
       createRouteFromActivity: "Route aus Aktivität erstellen",
     },
+    settings: {
+      title: "Einstellungen",
+      profile: {
+        title: "Profil",
+        displayName: "Anzeigename",
+        bio: "Bio",
+        saved: "Profil gespeichert.",
+      },
+      security: {
+        title: "Sicherheit",
+        description: "Verwalte deine Passkeys zum Anmelden.",
+        addPasskey: "Passkey hinzufügen",
+        passkey: "Passkey",
+        thisDevice: "Dieses Gerät",
+        securityKey: "Sicherheitsschlüssel",
+        bluetooth: "Bluetooth",
+        phoneOrTablet: "Telefon oder Tablet",
+        addedOn: "Hinzugefügt am {{date}}",
+        noPasskeys: "Keine Passkeys registriert. Du kannst dich per Magic Link anmelden.",
+        deleteConfirm: "Möchtest du diesen Passkey wirklich löschen?",
+        deleteLastWarning: "Dies ist dein einziger Passkey. Du musst Magic Links zum Anmelden verwenden. Trotzdem löschen?",
+      },
+      account: {
+        title: "Konto",
+        changeEmail: "Ändern",
+        newEmailPlaceholder: "Neue E-Mail-Adresse",
+        sendVerification: "Bestätigen",
+        verificationSent: "Bestätigungs-E-Mail gesendet. Prüfe deinen Posteingang.",
+        dangerZone: "Gefahrenzone",
+        deleteDescription: "Lösche dein Konto und alle zugehörigen Daten unwiderruflich.",
+        deleteAccount: "Konto löschen",
+        deleteConfirmPrompt: "Gib \"{{username}}\" ein, um die Löschung zu bestätigen:",
+        confirmDelete: "Endgültig löschen",
+      },
+    },
+    nav: {
+      routes: "Routen",
+      activities: "Aktivitäten",
+      login: "Anmelden",
+      register: "Registrieren",
+      profile: "Profil",
+      settings: "Einstellungen",
+      logout: "Abmelden",
+    },
     auth: {
       login: "Anmelden",
       register: "Registrieren",

packages/i18n/src/locales/en.ts

@@ -93,14 +93,6 @@ export default {
   journal: {
     title: "trails.cool",
     subtitle: "Your outdoor activity journal",
-    nav: {
-      routes: "Routes",
-      activities: "Activities",
-      login: "Sign In",
-      register: "Register",
-      profile: "Profile",
-      logout: "Log Out",
-    },
     welcome: "Welcome,",
     addPasskeyPrompt: "Add a passkey for faster sign-in on this device.",
     addPasskey: "Add Passkey",
@@ -130,6 +122,50 @@ export default {
       linkToRoute: "Link to Route",
       createRouteFromActivity: "Create Route from Activity",
     },
+    settings: {
+      title: "Settings",
+      profile: {
+        title: "Profile",
+        displayName: "Display Name",
+        bio: "Bio",
+        saved: "Profile saved.",
+      },
+      security: {
+        title: "Security",
+        description: "Manage your passkeys for signing in.",
+        addPasskey: "Add Passkey",
+        passkey: "Passkey",
+        thisDevice: "This device",
+        securityKey: "Security key",
+        bluetooth: "Bluetooth",
+        phoneOrTablet: "Phone or tablet",
+        addedOn: "Added {{date}}",
+        noPasskeys: "No passkeys registered. You can sign in with magic links.",
+        deleteConfirm: "Are you sure you want to delete this passkey?",
+        deleteLastWarning: "This is your only passkey. You will need to use magic links to sign in. Delete anyway?",
+      },
+      account: {
+        title: "Account",
+        changeEmail: "Change",
+        newEmailPlaceholder: "New email address",
+        sendVerification: "Verify",
+        verificationSent: "Verification email sent. Check your inbox.",
+        dangerZone: "Danger Zone",
+        deleteDescription: "Permanently delete your account and all associated data.",
+        deleteAccount: "Delete Account",
+        deleteConfirmPrompt: "Type \"{{username}}\" to confirm deletion:",
+        confirmDelete: "Permanently Delete",
+      },
+    },
+    nav: {
+      routes: "Routes",
+      activities: "Activities",
+      login: "Sign In",
+      register: "Register",
+      profile: "Profile",
+      settings: "Settings",
+      logout: "Log Out",
+    },
     auth: {
       login: "Sign In",
       register: "Register",