Show a red alert frame when the player is betrayed (#1195)

## Description:

With the alert frame, we're notified and can view the event using a
“Focus” button that moves the map to the traitor, or dismiss it with a
“Dismiss” button. The alert auto-dismisses after a few seconds.

**Because this feature provides an advantage, the trade-off is having to
wait a full 10 seconds or manually clicking “Dismiss” to close it.**

- Show a red alert frame animation when the player is betrayed.
- ~~The alert frame can be dismissed manually.~~
- The alert frame is automatically dismissed after ~~10~~ 3 seconds.
- If the user doesn’t want to see it at all, they can disable it in the
settings.

![Capture d’écran 2025-06-16 à 20 09
51](https://github.com/user-attachments/assets/2897ae16-85d6-4201-ac5b-e60b0cb18add)
![Capture d’écran 2025-06-16 à 20 10
24](https://github.com/user-attachments/assets/088edf08-20fe-4dae-8c00-cbcd24004bd0)
![Capture d’écran 2025-06-16 à 20 10
50](https://github.com/user-attachments/assets/894296aa-c753-429f-8c5d-edd881deec48)
![Capture d’écran 2025-06-16 à 20 11
14](https://github.com/user-attachments/assets/29503958-0042-4614-8db2-2663cadee441)

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

## Please put your Discord username so you can be contacted if a bug or
regression is found:

This is my first PR let me know if anything needs improvement!

devalnor

src/client/UserSettingModal.ts

@@ -102,6 +102,15 @@ export class UserSettingModal extends LitElement {
     console.log("🤡 Emojis:", enabled ? "ON" : "OFF");
   }
 
+  private toggleAlertFrame(e: CustomEvent<{ checked: boolean }>) {
+    const enabled = e.detail?.checked;
+    if (typeof enabled !== "boolean") return;
+
+    this.userSettings.set("settings.alertFrame", enabled);
+
+    console.log("🚨 Alert frame:", enabled ? "ON" : "OFF");
+  }
+
   private toggleFxLayer(e: CustomEvent<{ checked: boolean }>) {
     const enabled = e.detail?.checked;
     if (typeof enabled !== "boolean") return;
@@ -244,6 +253,15 @@ export class UserSettingModal extends LitElement {
         @change=${this.toggleEmojis}
       ></setting-toggle>
 
+      <!-- 🚨 Alert frame -->
+      <setting-toggle
+        label="${translateText("user_setting.alert_frame_label")}"
+        description="${translateText("user_setting.alert_frame_desc")}"
+        id="alert-frame-toggle"
+        .checked=${this.userSettings.alertFrame()}
+        @change=${this.toggleAlertFrame}
+      ></setting-toggle>
+
       <!-- 💥 Special effects -->
       <setting-toggle
         label="${translateText("user_setting.special_effects_label")}"