UX: only show global email disabled message in admin and preference areas (discourse#37998)

Currently when `disable_emails` is true, we show this banner on every
page:

<img width="2228" height="274" alt="image"
src="https://github.com/user-attachments/assets/9282cfff-dd17-4880-82bd-5375b0983df1"
/>

But it's now much easier to set up Discourse without email, so this
message can be irritating if it's globally persisted everywhere. This
change scopes it admin areas (/admin and /review) and in preferences
like /my/preferences/emails and my/preferences/notifications so that if
someone is confused about email not working, they'll still likely see
it, but it's not a nuisance otherwise.

Author: awesomerobot

frontend/discourse/app/components/global-notice.gjs

@@ -81,6 +81,16 @@ export default class GlobalNotice extends Component {
     return !this.router.currentRouteName.startsWith("wizard.");
   }
 
+  get #showEmailsDisabledNotice() {
+    const routeName = this.router.currentRouteName;
+    return (
+      routeName?.startsWith("admin") ||
+      routeName?.startsWith("review") ||
+      routeName === "preferences.emails" ||
+      routeName === "preferences.notifications"
+    );
+  }
+
   get notices() {
     let notices = [];
 
@@ -147,8 +157,7 @@ export default class GlobalNotice extends Component {
           text: i18n("emails_are_disabled"),
           id: "alert-emails-disabled",
           options: {
-            dismissable: true,
-            persistentDismiss: false,
+            visibility: () => this.#showEmailsDisabledNotice,
           },
         })
       );
@@ -158,8 +167,7 @@ export default class GlobalNotice extends Component {
           text: i18n("emails_are_disabled_non_staff"),
           id: "alert-emails-disabled",
           options: {
-            dismissable: true,
-            persistentDismiss: false,
+            visibility: () => this.#showEmailsDisabledNotice,
           },
         })
       );

frontend/discourse/tests/acceptance/email-notice-test.js

@@ -19,33 +19,37 @@ acceptance("Email Disabled Banner", function (needs) {
 
   test("when enabled", async function (assert) {
     this.siteSettings.disable_emails = "yes";
+
     await visit("/latest");
     assert
       .dom(".alert-emails-disabled")
-      .exists("alert is displayed when email disabled");
+      .doesNotExist("alert is not displayed on non-admin routes");
+
+    updateCurrentUser({ admin: true });
+    await visit("/admin");
+    assert
+      .dom(".alert-emails-disabled")
+      .exists("alert is displayed on admin routes when email disabled");
     assert
       .dom(".alert-emails-disabled .text")
       .hasText(i18n("emails_are_disabled"), "alert uses the correct text");
   });
 
   test("when non-staff", async function (assert) {
     this.siteSettings.disable_emails = "non-staff";
-    await visit("/");
+
+    await visit("/latest");
     assert
       .dom(".alert-emails-disabled")
-      .exists("alert is displayed when email disabled for non-staff");
-    assert
-      .dom(".alert-emails-disabled .text")
-      .hasText(
-        i18n("emails_are_disabled_non_staff"),
-        "alert uses the correct text"
-      );
+      .doesNotExist("alert is not displayed on non-admin routes");
 
-    updateCurrentUser({ moderator: true });
-    await visit("/");
+    updateCurrentUser({ admin: true });
+    await visit("/admin");
     assert
       .dom(".alert-emails-disabled")
-      .exists("alert is displayed to staff when email disabled for non-staff");
+      .exists(
+        "alert is displayed on admin routes when email disabled for non-staff"
+      );
     assert
       .dom(".alert-emails-disabled .text")
       .hasText(