Update homepage & in-game promos (#3602)

## Description:

* Replace the static footer ad (HomeFooterAd component) with a Playwire
bottom_rail ad that loads on lobby join and persists into the spawn
phase
* Expand in-game ad slots from 1 to 3 (standard_iab_left1, left3, left4)
with a timer-based visibility check to show a background container when
ads render
* Remove the resize-based footer ad height logic and gutter ad vertical
offset adjustments that depended on it

<img width="1828" height="961" alt="Screenshot 2026-04-16 at 12 14
00 PM"
src="https://github.com/user-attachments/assets/50bfd0de-dd54-4f8b-b75e-04b720a1841b"
/>


<img width="1286" height="939" alt="Screenshot 2026-04-16 at 11 59
18 AM"
src="https://github.com/user-attachments/assets/e0fb0762-82e7-444f-8706-5908aad0f094"
/>
## 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

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

evan

src/client/Main.ts

@@ -28,7 +28,7 @@ import { GameModeSelector } from "./GameModeSelector";
 import { GameStartingModal } from "./GameStartingModal";
 import "./GoogleAdElement";
 import { HelpModal } from "./HelpModal";
-import { HomepagePromos } from "./HomepagePromos";
+import "./HomepagePromos";
 import { HostLobbyModal as HostPrivateLobbyModal } from "./HostLobbyModal";
 import { JoinLobbyModal } from "./JoinLobbyModal";
 import "./LangSelector";
@@ -58,6 +58,7 @@ import {
   isInIframe,
   translateText,
 } from "./Utils";
+
 import "./components/DesktopNavBar";
 import "./components/Footer";
 import "./components/MainLayout";
@@ -303,10 +304,6 @@ class Client {
       }
     });
 
-    const gutterAds = document.querySelector("homepage-promos");
-    if (!(gutterAds instanceof HomepagePromos))
-      throw new Error("Missing homepage-promos");
-
     document.addEventListener("join-lobby", this.handleJoinLobby.bind(this));
     document.addEventListener("leave-lobby", this.handleLeaveLobby.bind(this));
     document.addEventListener("kick-player", this.handleKickPlayer.bind(this));