Make SpawnAd loading text translatable using translateText (#1393)

## Description:
Replaced the hardcoded "loading" text in the SpawnAd component with
`translateText("spawn_ad.loading")` for proper localization.

## 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:

aotumuri

resources/lang/en.json

@@ -576,6 +576,9 @@
       "grogu": "Grogu"
     }
   },
+  "spawn_ad": {
+    "loading": "Loading advertisement..."
+  },
   "auth": {
     "login_required": "Login is required to access this website.",
     "redirecting": "You are being redirected...",

src/client/graphics/layers/SpawnAd.ts

@@ -1,5 +1,6 @@
 import { LitElement, css, html } from "lit";
 import { customElement, state } from "lit/decorators.js";
+import { translateText } from "../../../client/Utils";
 import { GameView } from "../../../core/game/GameView";
 import { getGamesPlayed } from "../../Utils";
 import { Layer } from "./Layer";
@@ -123,7 +124,9 @@ export class SpawnAd extends LitElement implements Layer {
           class="w-full h-full flex items-center justify-center"
         >
           ${!this.adLoaded
-            ? html`<span class="text-white text-sm">Loading ad...</span>`
+            ? html`<span class="text-white text-sm"
+                >${translateText("spawn_ad.loading")}</span
+              >`
             : ""}
         </div>
       </div>